July 02, 2026

Another Round of Damaging Storms Could Hit Southern Ontario Thursday With Tornado Risk Increasing

July 02, 2026/ Brennen Perry

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After an active Canada Day that saw storms sweep through Southern Ontario, causing damage and power outages from widespread damaging wind gusts, Thursday may feel like déjà vu for some areas. For parts of the province, this could be the third severe weather risk of the week.

Fueling all of this active weather is the ongoing heat event, which has led to temperatures soaring into the mid to upper 30s across many locations. Thursday is expected to be similarly hot, creating more than enough instability for another round of severe weather.

While Wednesday’s risk was mainly focused on damaging wind gusts, Thursday could feature a more defined tornado risk, with one or two tornadoes possible. The focus of this tornado risk appears to be in Southwestern Ontario near the Lake Huron shoreline, along with parts of Eastern Ontario, including the Ottawa Valley.

The damaging wind gust threat also remains very present. Similar linear-like storms could sweep through a corridor from Lake Huron into the GTA, and then toward the Lake Simcoe, Peterborough and Kingston areas.

Up to Timbit-sized hail is also possible, especially across Eastern Ontario, along the Lake Huron shoreline and around the London area. In these regions, a more isolated storm mode could support a few supercell thunderstorms.

Once again, models are struggling to pinpoint exactly when and where storm development will happen. They tend to perform poorly in these types of dynamic setups, especially when storms are triggered by smaller-scale features such as lake breezes and outflow boundaries from other storms.

What we do know is where the strongest environment is located, along with a rough idea of where models are most likely to develop storms.

That begins during the afternoon, when we could see isolated cells develop from the Lake Simcoe area down toward Kingston. These storms could support a tornado risk, which is why this corridor is also highlighted on our map for tornado potential.

However, confidence is lower in this area. Not every model shows storm development, so this part of the forecast will depend heavily on whether the right triggers are in place.

Another zone of possible storm development can be found across the Ottawa Valley and Eastern Ontario during the evening. A strong shear environment could support rotation if storms are able to develop.

Similar to the afternoon Lake Simcoe risk, confidence is lower here because not all models show storm development. The threat will depend on whether storms can actually form and take advantage of the environment.

The Lake Huron storms may eventually merge into a larger complex and bring a potential late-night damaging wind gust risk through the GTA and Niagara region.

There is still some question about how long this complex would be able to maintain its strength, especially once we lose daytime heating. However, if it holds together, damaging wind gusts could once again become a concern.

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Overall, the forecast for Thursday looks quite similar to Wednesday. We have a “Strong” (Level 3/5) severe risk across a large area, but this time it also includes portions of Deep Southwestern Ontario, including the Sarnia and London areas, along with the Golden Horseshoe.

Other locations included in this risk zone are Goderich, Owen Sound, Kitchener, Hamilton, Guelph, Toronto, Newmarket, Barrie, Orillia, Peterborough, Belleville and Kingston.

This risk is being driven by the potential for strong wind gusts within this corridor, with multiple linear storms possible. If these storms can organize, they could lead to widespread wind damage. There is also the risk for up to Timbit-sized hail and one or two tornadoes.

We have a “Widespread” (Level 2/5) severe risk for Windsor, Chatham and the Lake Erie shoreline, extending into the Niagara region. There is also another “Widespread “ risk zone through Muskoka, Algonquin Park, Bancroft and the Ottawa Valley.

These areas are outside the zone most likely to see the most widespread damaging wind gusts, so the primary threat here will be driven by up to Timbit-sized hail and the risk for one or two tornadoes.

Another major concern is flooding, especially in the Ottawa Valley. This region saw significant flooding on Wednesday after more than 100 mm of rain fell in some areas. Flooding could once again become a serious issue if storms linger over the same communities or repeatedly track over the Ottawa area.

For northern sections of Central Ontario into Northeastern Ontario, including North Bay, Sudbury and Elliot Lake, we have an “Isolated” (Level 1/5) severe risk. We are not expecting widespread severe weather in this area, but with so much energy in the atmosphere, we cannot rule out an isolated pop-up storm capable of becoming severe.

July 01, 2026

Strong Severe Storm Risk Threatens Canada Day Across Southern Ontario, Damaging Winds and Isolated Tornadoes Possible

July 01, 2026/ Brennen Perry

Hot and humid weather has arrived across Southern Ontario just in time for Canada Day, with temperatures soaring into the mid-to-upper 30s, with the humidex making it feel into the 40s. While many will be heading outside to celebrate, this intense heat is also creating an atmosphere that is primed for severe thunderstorms later today.

Unfortunately, this stormy weather could put a damper on Canada Day celebrations, particularly across portions of Southwestern, Central and Eastern Ontario.

We are tracking a conditional severe weather threat for Wednesday afternoon and evening, with the risk potentially continuing into the overnight hours. The hot, humid air will provide plenty of fuel for thunderstorm development. Wherever storms are able to form, they could rapidly become severe thanks to the extremely unstable atmosphere.

In addition to isolated storm development, there is also the potential for one or more organized linear complexes of thunderstorms to move through Southern Ontario. If these systems develop and hold together, they could produce widespread damaging wind gusts across a large portion of the province.

We continue to describe today's threat as conditional because forecast models are doing a poor job of determining exactly where storms will develop. We know the environment is more than capable of supporting severe thunderstorms, but storms first need to form in order to take advantage of the available instability.

Development may be triggered by lake breeze boundaries, leftover outflow boundaries from earlier storms, or other small-scale features that are notoriously difficult to predict ahead of time. As a result, not everyone will see a thunderstorm today, but those that do could experience very intense conditions.

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As of 1 PM, we're already watching a strong complex of thunderstorms developing over Northern Michigan that is tracking toward Lake Huron and eventually Southwestern Ontario by the mid to late afternoon. If this complex is able to maintain its strength as it crosses into Ontario, it could produce widespread damaging wind gusts from areas east of Lake Huron through the Lake Simcoe region and eventually into Eastern Ontario.

Additional thunderstorms may also develop later today across Quebec before sweeping into portions of Eastern Ontario and the Ottawa Valley during the evening and early overnight hours.

Outside of these organized storm complexes, isolated thunderstorms may develop almost anywhere across Southern Ontario this afternoon and evening. If they are able to establish themselves before merging into larger clusters, a few discrete supercells could develop.

These storms would be capable of producing damaging wind gusts, hail up to the size of Timbits and an isolated tornado. While the tornado threat appears highest across Eastern Ontario, an isolated tornado cannot be ruled out anywhere in Southern Ontario today.

We have a 'Strong' (Level 3/5) severe weather risk for locations including Goderich, Kincardine, Owen Sound, Hanover, Collingwood, Midland, Barrie, Orillia, Bracebridge, Peterborough, Tweed, Bancroft, Smiths Falls, Renfrew, Ottawa, Brockville and Cornwall. This higher risk is primarily driven by the potential for widespread damaging wind gusts this afternoon and evening, although large hail and an isolated tornado are also possible.

Surrounding areas, including Grand Bend, Woodstock, Kitchener, Guelph, Hamilton, Toronto, Newmarket, Oshawa and Kingston, are under a 'Widespread' (Level 2/5) severe weather risk. These locations could also experience damaging wind gusts if storm complexes hold together, although the tornado risk is somewhat lower compared to Central and Eastern Ontario.

We also have an 'Isolated' (Level 1/5) severe weather risk across the rest of Deep Southwestern Ontario, along with the Niagara region. While storm coverage is expected to remain limited here, any storm that does develop could quickly become severe given the highly unstable environment.

Farther north, we have gone with an 'Widespread' (Level 2/5) to 'Isolated' (Level 1/5) severe weather risk across northern portions of Central Ontario, including North Bay and Sudbury. Storms that develop in this region could strengthen before tracking south and eastward into Quebec and Eastern Ontario.

The severe weather threat should gradually diminish around midnight. However, thunderstorms may continue overnight as the atmosphere will remain exceptionally unstable despite the loss of daytime heating. If a mature storm complex is able to move through overnight, isolated severe weather will remain possible, with damaging wind gusts posing the primary threat.

June 29, 2026

Multiple Tornadoes and Tennis Ball Sized Hail Possible Monday Across Manitoba and Northwestern Ontario

June 29, 2026/ Brennen Perry

After a destructive severe weather outbreak that brought violent tornadoes to Western Manitoba on Sunday, the risk shifts eastward into Winnipeg, Eastern Manitoba and Northwestern Ontario on Monday.

Based on the latest forecast data, today's storms could bring a similarly dangerous setup with the potential for significant severe weather, including multiple tornadoes, huge hail up to the size of tennis balls, destructive wind gusts in excess of 100 km/h, and areas of flash flooding.

The greatest concern is across areas just southeast of Winnipeg where we have issued a 'significant' severe weather risk. This includes Winkler, Steinbach, Kenora, Dryden, Atikokan and Fort Frances.

Storms that develop in this corridor will have the potential to rapidly become powerful supercells capable of producing all severe weather hazards. The tornado threat is expected to be highest in this zone where atmospheric conditions appear most favourable for rotating thunderstorms.

A 'strong' severe weather risk extends across the rest of South-central and Eastern Manitoba, including Winnipeg, Portage la Prairie, Carman, Killarney, Selkirk, Gimli, Ashern, Arborg, Peguis, Pine Falls, Red Lake, Sioux Lookout and Thunder Bay.

While damaging wind gusts and large hail will likely be the primary hazards across much of this area, an isolated tornado cannot be ruled out, especially across South-central Manitoba and the Interlake region where conditions may still support discrete rotating storms before they begin to organize into larger clusters.

Farther west, there is a widespread to isolated severe weather risk across Western Manitoba, including Brandon, Virden, Dauphin, Roblin and Swan River. Flooding is expected to be the biggest concern in this region as slow-moving thunderstorms could repeatedly track over the same communities.

Rainfall totals could exceed 100 mm in localized areas, leading to flash flooding. An isolated tornado also cannot be ruled out around the Brandon area during the afternoon should any storms remain isolated long enough to become organized.

**SIMULATED RADAR** - MAP FROM WEATHERBELL

Today's severe weather threat is expected to begin during the afternoon with slow-moving thunderstorms developing across Western Manitoba, particularly near the Brandon area.

These storms will move very little, increasing the risk of training thunderstorms where multiple storms repeatedly pass over the same locations.

This could quickly lead to localized flooding, but these storms may also be capable of producing large hail, damaging wind gusts and even an isolated tornado.

The primary severe weather outbreak is expected to unfold later in the afternoon and into the early evening as isolated thunderstorms develop along the international border from Winkler eastward through Southeastern Manitoba and into Fort Frances in Northwestern Ontario.

The atmosphere during this period is expected to be highly supportive of supercell development. Any storm that can remain isolated will have the potential to produce tornadoes, very large hail and destructive wind gusts.

Hail could reach the size of tennis balls in the strongest storms, which would be capable of causing significant damage to vehicles, roofs and crops.

Winnipeg sits near the northwestern edge of the greatest severe weather threat. While current guidance keeps the most dangerous storms just southeast of the city, even a small shift farther west could bring a much higher tornado risk into the Winnipeg area.

The tornado threat should gradually decrease after sunset as daytime heating fades and the atmosphere becomes less favourable for discrete supercells. However, that will not mark the end of the severe weather threat.

As the evening progresses, many of the isolated storms are expected to merge into one or more organized lines of thunderstorms. While the tornado risk will lessen, these storm lines could produce widespread destructive wind gusts capable of causing tree damage, power outages and structural damage across parts of Manitoba and Northwestern Ontario.

These storms could reach the Winnipeg and Thunder Bay regions around midnight with another round of severe weather. Although the primary concern overnight will shift toward damaging straight-line winds, an isolated nocturnal tornado cannot be completely ruled out.

The severe weather threat should come to an end across Manitoba after midnight as the storm complex moves eastward. However, portions of Northwestern Ontario may continue to see strong to severe thunderstorms into Tuesday morning before the system gradually weakens and exits the region.

June 27, 2026

Tornado Risk for Regina Area as Significant Severe Storm Risk Target Saskatchewan & Manitoba Saturday

June 27, 2026/ Brennen Perry

After a brief reprieve from active weather across Saskatchewan and Western Manitoba, the threat of severe thunderstorms returns on Saturday. This round of storms could bring a potentially significant severe weather risk to portions of Southeastern Saskatchewan, especially around Weyburn and Estevan.

Isolated thunderstorms are expected to develop near the International Border around the dinner hour. Any storms that form could quickly become supercells capable of producing all severe weather hazards, including tornadoes, golf ball-sized hail and destructive wind gusts up to 120 km/h.

There is also a strong severe weather risk extending northward toward Assiniboia, Moose Jaw and Regina. An isolated tornado cannot be ruled out in these areas as well, although confidence in storm development is lower compared to locations closer to the border.

Further south, additional thunderstorms are expected to develop across Montana and North Dakota. As the evening progresses, these storms are forecast to merge into a large complex that will race northeast toward Saskatchewan and Southwestern Manitoba.

The earlier isolated supercells over Southeastern Saskatchewan are expected to be absorbed into this larger storm complex as it crosses the border. As this happens, the primary threat will shift from large hail and tornadoes to widespread damaging wind gusts as the storms organize into a fast-moving line during the mid and late evening hours.

This line is expected to sweep northeast from Regina toward the Manitoba border. There is still some uncertainty regarding how well it will maintain its strength after sunset, as the loss of daytime heating will reduce available instability. However, we expect at least an isolated to widespread severe weather risk to continue past midnight as the storms approach the Yorkton and Brandon corridor.

Based on the latest data, isolated thunderstorms are most likely to develop between 5 and 7 PM CST near the International Border. These storms could impact the Weyburn and Estevan areas as they rapidly intensify into supercells capable of producing large hail, damaging wind gusts and tornadoes.

The environment will be particularly favourable for tornadic development during the first few hours of these storms' lifespan. The greatest tornado risk appears to be closest to the border, although this threat could extend northwest toward Moose Jaw and Regina if storms are able to develop there during the late afternoon and early evening.

As the mature line of storms over Montana and North Dakota advances into Saskatchewan, the earlier isolated storms are expected to merge into the line, forming a bowing segment stretching from Regina to the Manitoba border.

Although the tornado threat will decrease once the storms become linear, a brief QLCS spin-up tornado cannot be ruled out, particularly near any bookend vortices that develop within the line. The primary hazard, however, will become widespread damaging wind gusts, with localized gusts over 100 km/h possible. The hail threat will also diminish by this stage, although quarter to toonie-sized hail may still accompany the strongest storms.

The line will continue sweeping across Southeastern Saskatchewan and into Southwestern Manitoba during the overnight hours. While isolated damaging wind gusts will remain possible within the strongest portions of the line, there is still uncertainty regarding how well the storms will maintain their intensity after midnight.

June 25, 2026

Southern Ontario Faces Severe Storm and Tornado Risk Thursday Ahead of Possible Canada Day Heatwave

June 25, 2026/ Brennen Perry

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While the latter half of June has been relatively quiet across Southern Ontario when it comes to severe weather, thanks to cooler temperatures dominating the region, that pattern is about to change in a big way. As we head into the final days of June, much warmer and increasingly humid air will begin pushing into the province, bringing with it a rapidly increasing risk for thunderstorms.

The first significant opportunity arrives on Thursday, when portions of Southwestern Ontario could see a widespread severe thunderstorm risk. An isolated severe threat may also extend farther east into parts of the Golden Horseshoe and Central Ontario.

If thunderstorms are able to develop during the afternoon and early evening, they will move into a very favourable environment capable of supporting supercell thunderstorms. These storms could produce all modes of severe weather, including toonie-sized hail or larger, damaging wind gusts in excess of 100 km/h, torrential rainfall and even a few isolated tornadoes.

The most favourable environment currently appears to be across areas including Sarnia, Chatham, Grand Bend, Goderich and London. However, isolated thunderstorms could also develop as far north as the Bruce Peninsula, east toward Lake Simcoe, and south into portions of the Greater Toronto Area. While the tornado threat decreases farther away from Lake Huron, it cannot be completely ruled out as far east as Kitchener, Hamilton and portions of the southern Georgian Bay shoreline.

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Thursday's forecast does come with one important complication. Morning showers and non-severe thunderstorms are expected to move through Southwestern Ontario before spreading into Central and Eastern Ontario during the day.

As we've seen many times before, morning convection can make or break an afternoon severe weather event. If clouds and showers linger too long, they can prevent the atmosphere from recovering enough to support stronger storms later in the day.

On the other hand, if skies clear by around the noon hour, as many of the latest models suggest, there should be several hours available for temperatures and instability to quickly rebound.

**Significant Tornado Parameter** - MAP FROM WEATHERBELL

By the mid-afternoon, the atmosphere is expected to become increasingly supportive of severe thunderstorms, with the highest risk developing between roughly 2 PM and 6 PM. The strongest combination of instability and wind shear currently appears to be centred near the Lake Huron shoreline, extending into Sarnia and Chatham.

The latest Significant Tornado Parameter (STP) data also highlights an enhanced corridor stretching from the Michigan border across Lake Huron into Southwestern Ontario. Should storms form within this corridor, they could rapidly intensify into rotating supercells capable of producing very large hail, damaging winds and isolated tornadoes.

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There remains some disagreement among the forecast models regarding exactly where storms will first develop.

Some models initiates storms as early as 3 PM across Michigan before they quickly cross into Deep Southwestern Ontario. This scenario would place communities such as Sarnia, Grand Bend, Goderich and London at the greatest risk.

Other models delay development until later in the afternoon or early evening, with storms forming closer to the Hanover to Grand Bend corridor before tracking southeast toward London, Kitchener and possibly Hamilton. Regardless of which solution verifies, the greatest tornado potential continues to favour areas along and just inland from the southeastern Lake Huron shoreline.

Additional isolated thunderstorms may also develop around Lake Simcoe and into the Greater Toronto Area during the late afternoon and early evening. While the environment in these areas appears less favourable for widespread severe weather, a few stronger storms cannot be ruled out. The primary threats would be hail up to quarter size along with isolated damaging wind gusts.

As the sun sets Thursday evening, the severe weather threat should gradually diminish as daytime heating is lost. However, scattered non-severe showers and thunderstorms may continue well into the overnight hours, particularly across Central and Eastern Ontario.

Looking beyond Thursday, the severe weather threat briefly settles down. Friday may bring a very isolated thunderstorm risk across Eastern Ontario, particularly near the Ottawa Valley, while much of the weekend currently appears relatively quiet from a severe weather perspective.

The bigger story heading into next week will likely be the return of significant heat.

Temperatures are expected to steadily climb through the weekend, with many areas approaching or exceeding 30°C by Monday. Current medium-range guidance suggests the heat could continue to intensify into the middle of next week, potentially peaking around Canada Day.

Some forecast models are indicating temperatures running between 5 and 10°C above seasonal averages, with localized anomalies approaching 15°C in parts of Ontario on Canada Day. If those projections verify, daytime highs could reach the low to mid 30s across portions of both Southern and Northern Ontario.

When combined with increasing humidity, it may feel close to 40°C in many communities.

This surge of heat and humidity will also provide plenty of fuel for additional thunderstorm development. While it is still too early to determine exactly which days will carry the greatest severe weather risk, there are increasing signs that we could be entering a much more active pattern over the next one to two weeks. Exactly when storms develop will depend on the arrival of cold fronts and other triggering mechanisms, something that will become much clearer once higher resolution models come into range.

We'll continue monitoring both Thursday's severe weather potential and the possible prolonged heat event expected next week. Stay tuned for forecast updates throughout the coming days as confidence continues to increase.

June 17, 2026

Powerful June Storm System Could Bring Damaging Winds and Isolated Tornadoes to Southern Ontario Overnight

June 17, 2026/ Brennen Perry

An unusually strong and deepening low pressure system for mid-June is set to track through the Great Lakes region overnight Wednesday and into Thursday. This powerful system will bring the potential for severe weather to a large portion of Southern Ontario, with the greatest threat occurring late tonight and into Thursday morning.

The same system is expected to produce a significant severe weather outbreak across portions of Illinois, Indiana and Michigan this afternoon and evening. In those areas, forecasters are highlighting the risk of violent tornadoes, destructive wind gusts and large hail as a potent combination of instability and wind shear develops ahead of the approaching low pressure system.

As this line of storms pushes eastward into Michigan tonight, it is expected to gradually weaken before reaching Ontario. However, weakening does not necessarily mean the severe threat will disappear.

Even in a decaying state, this line of storms could still bring impactful weather to portions of Southwestern Ontario, especially areas closest to the international border and along the Lake Huron shoreline.

Based on the latest forecast data, the primary threat appears to be damaging wind gusts in excess of 100 km/h. In localized areas, stronger wind gusts could occur if isolated downbursts develop within the line of storms. These stronger pockets of wind have the potential to cause tree damage, power outages and scattered property damage.

While the tornado threat will be considerably lower than what is expected across parts of the United States, it cannot be completely ruled out.

The atmosphere over Deep Southwestern Ontario will remain supportive of some rotation early in the night, particularly while the line of storms is still relatively organized. Any tornado risk would likely be brief and localized in nature, but the strong dynamics associated with this system mean it is something we will be watching closely.

Another factor adding complexity to this forecast is the strength of the low pressure system itself.

In addition to thunderstorm-related winds, very strong winds will be present just above the surface overnight. Normally, a temperature inversion would act as a lid and prevent those stronger winds from mixing down to ground level. Current indications suggest that inversion should remain in place for much of the night.

However, if portions of that stronger wind are able to reach the surface, isolated non-thunderstorm wind gusts in excess of 90 km/h would be possible. This risk appears highest near the shorelines of Lake Huron and Lake Erie where local effects can help enhance wind gusts.

We’ll be closely monitoring this severe weather threat throughout the evening and overnight hours.

If conditions warrant, we’ll be going live on our YouTube channel with real-time storm tracking, radar analysis, warning updates and coverage of any severe weather that develops across Southern Ontario.

Be sure to subscribe to our YouTube channel HERE and turn on notifications so you don’t miss any live coverage. Whether it’s damaging winds, tornado warnings or rapidly changing conditions, we’ll be there to keep you informed every step of the way.

Heavy rainfall will also accompany this system. Many areas will receive beneficial rainfall, but localized torrential downpours could lead to rainfall amounts exceeding 50 mm in a relatively short period of time. If storms repeatedly move over the same area, flash flooding could develop, especially in urban locations and areas with poor drainage.

The highest severe weather risk tonight stretches across Deep Southwestern Ontario and portions of the Lake Huron shoreline. This includes Windsor, Leamington, Chatham, Sarnia, Grand Bend, Goderich and Kincardine.

In these areas, storms could begin arriving as early as 8 to 9 PM and continue through the overnight hours. Damaging wind gusts remain the primary concern, although heavy rain and an isolated tornado cannot be ruled out.

As the line progresses eastward, it is expected to reach the London, Woodstock, Kitchener, Guelph, Orangeville and Hanover areas around or shortly after midnight. There remains some uncertainty regarding exactly how much strength the storms will retain by this point. However, the potential still exists for several pockets of damaging winds to survive farther inland.

The tornado threat should be lower compared to areas farther west, but strong winds and localized flooding will continue to be concerns as the line moves through.

By the time the storms reach Central Ontario and the Golden Horseshoe during the overnight hours, the severe threat should be decreasing further. That said, this remains a powerful weather system and some stronger portions of the line could still produce isolated wind gusts approaching 90 km/h.

As a result, we continue to highlight an isolated severe weather risk for Toronto, Hamilton, Niagara, Newmarket, Barrie, Orillia, Bracebridge, Peterborough and Bancroft.

Attention will then shift to Eastern Ontario during the early morning hours on Thursday. Unlike areas farther west, there are indications that the atmosphere may begin to recover somewhat as the main line approaches. There is also the potential for additional isolated thunderstorms to develop behind or ahead of the main line shortly after sunrise.

This could allow for a secondary severe weather threat across portions of Eastern Ontario, particularly near the international border and into the Ottawa Valley. This broader morning severe weather risk includes Kingston, Brockville, Smiths Falls, Cornwall, Ottawa and Picton.

Should additional storms develop within this environment, all severe weather hazards would be possible including damaging wind gusts, heavy rainfall, hail and even an isolated tornado.

Forecast confidence in the tornado threat remains lower due to the early morning timing and questions surrounding how much instability can develop. However, the environment bears watching closely given the strength of the overall weather system.

The severe weather threat is expected to gradually come to an end from west to east through Thursday morning, with most areas seeing the risk diminish by early afternoon.

Even after thunderstorms exit the region, conditions will remain quite blustery throughout the day. Strong non-thunderstorm wind gusts may continue across much of Southern Ontario as the powerful low pressure system pulls away from the Great Lakes.

June 09, 2026

Potential Derecho Combined with Threat of Baseball Hail and Tornadoes Marks the Return of Extreme Risk in Saskatchewan and Manitoba Tuesday

June 09, 2026/ Alannah Campbell

It was a very busy weekend for severe weather in Southeastern Saskatchewan and Southwestern Manitoba. From the two day span, there have been countless reports of massive hail, wind damage, flooding from across the region, as well as a few tornado reports that are awaiting confirmation. Unfortunately, the calmer conditions we saw on Monday will come to an end when strong severe thunderstorms once again impact Southern Saskatchewan and Manitoba today.

Through the day, a low pressure system will strengthen as it moves from Southeastern Montana into Western North Dakota and then into Southeastern Saskatchewan and Southwestern Manitoba by later this afternoon. A warm front will extend eastward from the low pressure center, which will help draw lots of heat and moisture northward into Southern Saskatchewan and Manitoba.

***Future Surface weather map with the positions of highs, lows, and fronts displayed for 12pm cst/1pm CDT on Tuesday, courtesy of*** ***the national weather service***.

Temperatures are slated to climb into upper 20s and low 30s across the region this afternoon and with dewpoints expected to be in the upper teens, there will be plenty of fuel for thunderstorm development. Weather models are showing upwards of 4000J/kg of CAPE in some areas, which will support the development of supercell thunderstorms. Veering winds will also create a significant amount of shear to maintain large supercell thunderstorms and support tornado potential.

Through the morning, there is a chance that some thunderstorms could develop in Southeastern Saskatchewan which would track northeastward into Southwestern Manitoba during the early afternoon. These storms could possibly become severe and produce some small hail and strong winds, but they won’t be as strong as the storms expected later in the day.

***Simulated reflectivity at 3pm CST/4pm CDT, courtesy of weatherbell.***

Severe thunderstorms could start to fire up in the early afternoon, particularly in Southwestern and West Central Saskatchewan. However, we will gradually see more organized development of stronger thunderstorms occur across Southern Saskatchewan and into Southwestern Manitoba as we get later in the afternoon, around 3-6pm, depending on the time zone.

Similar to what we saw on the weekend, the thunderstorms are expected to grow exponentially into large supercells which will track mostly northeastward through the evening and overnight.

***Simulated reflectivity at 7pm CST/8pm CDT, courtesy of weatherbell.***

Even more thunderstorms are expected develop during the evening and storms will also move into the region from south of the border. As with the situation on both Saturday and Sunday, there is the likelihood that these additional storms will end up merging into a large line of thunderstorms. These thunderstorms will continue to be quite strong for a few hours after they transition into a linear storm mode.

As the hours tick on and it gets closer to midnight, it’s likely that the storms will begin to gradually weaken. This is also around the time that the severe line will make its way into the Winnipeg area so it’s possible that the city could avoid the greatest severe hazards of the day.

***Simulated reflectivity at 11pm CST/12am CDT, courtesy of weatherbell.***

The risk of strong severe thunderstorms extends across much of Southern Saskatchewan and Manitoba today. Across much of the region, there will be the possibility for storms to produce ping pong ball hail, damaging wind gusts up to 100km/h, and heavy rains that will likely result in localized flooding.

However, the greatest threat of severe weather will once again be in Southeastern Saskatchewan, into Southwestern Manitoba and extending eastward into the Interlake Region and approaching the Red River Valley. This region, highlighted in red and purple on our forecast map, could see some exceptionally strong thunderstorms this evening that will originate from Montana.

The main threat from the thunderstorms that move through this region is expected be widespread destructive wind gusts upwards of 130km/h and this could very likely end up being considered a derecho. On top of this, the storms will also have torrential downpours that could further exacerbate the flooding issues being faced by some communities and they may produce hail that could be as large as baseballs, which could be extremely dangerous if it’s being driven by winds up to 130km/h. As if this wasn’t enough, there is also a tornado risk across this region.

The major hindrance to tornado development over the weekend was that a lack of moisture ended up keeping the cloud bases high, until they were able to lower later in the evening on Sunday. This could end up being the case today, but this still has the potential to be a life-threatening situation.

Even without the tornado risk, today’s severe weather threat is very serious. If you live in the area that we’ve highlighted in either red or purple on our map, PLEASE be prepared for the likelihood that threatening weather could impact your area today. Make sure you have your phones charged and you have multiple ways to receive weather alerts. It’s also a good idea to have a plan in place in the event that you need to take shelter.

June 08, 2026

Threat of Large Hail, Damaging Winds and Tornadoes Returns to Saskatchewan and Manitoba on Tuesday

June 08, 2026/ Alannah Campbell

It was a very busy weekend for severe weather in Southeastern Saskatchewan and Southwestern Manitoba. From the two day span, there have been countless reports of massive hail, wind damage, flooding from across the region, as well as a few tornado reports that are awaiting confirmation. Unfortunately, Monday’s calmer conditions won’t last because strong severe thunderstorms are once again expected to impact Southern Saskatchewan and Manitoba on Tuesday.

Early Tuesday, a low pressure system will move into Southeastern Montana and from there, it will strengthen as it tracks into Western North Dakota through the morning hours and into the afternoon. A warm front will extend eastward from the low pressure center, which will help draw lots of heat and moisture northward into Southern Saskatchewan and Manitoba.

Temperatures are slated to climb into upper 20s and low 30s across the region in the afternoon and with dewpoints expected to be in the upper teens, there will be plenty of fuel for thunderstorm development. Some models are showing upwards of 4000J/kg of CAPE in some areas, which will support the development of supercell thunderstorms.

Veering winds will also create a significant amount of shear to maintain large supercell thunderstorms and support tornado potential. Overall, this is looking like a fairly similar environmental setup to Sunday.

During the late morning, there is a chance that some thunderstorms could develop in Southeastern Saskatchewan which would track northeastward into Southwestern Manitoba into the early afternoon hours. These storms will likely become severe and produce some small hail and strong winds, but they won’t be as strong as the storms expected later in the day. However, if these storms manage to persist across the Interlake Region, they could end up re-intensifying through the late afternoon and evening.

***Simulated reflectivity at 4pm CST/5pm CDT, courtesy of weatherbell.***

The strong severe thunderstorms could start to fire up in the early afternoon, particularly in Southwestern and West Central Saskatchewan. However, we will gradually see more organized development occur across Southern Saskatchewan and into Southwestern Manitoba as we get later in the afternoon, around 3-6pm, depending on the time zone.

Similar to what we saw on the weekend, the thunderstorms are expected to grow exponentially into large supercells which will track mostly northeastward through the evening and overnight.

***Simulated reflectivity at 8pm CST/9pm CDT, courtesy of weatherbell.***

More thunderstorms are expected develop during the evening and storms will also move into the region from south of the border. As with the situation on both Saturday and Sunday, there is the likelihood that these additional storms will end up merging into a large line of thunderstorms. These thunderstorms will continue to be quite strong for a few hours after they transition into a linear storm mode.

The risk of strong severe thunderstorms on Tuesday extends across much of Southern Saskatchewan and Manitoba. Throughout this region, the severe thunderstorms could end up producing hail that’s larger than golf balls, widespread damaging wind gusts up to 130km/h, and torrential downpours that could exacerbate the flooding issues some communities are already dealing with.

There is also the potential for tornadoes to form from these thunderstorms. The major hindrance to tornado development over the weekend was that a lack of moisture ended up keeping the cloud bases high until they were able to lower later in the evening on Sunday. This could end up being the case on Tuesday, given the similar environmental setup, but the risk is certainly still in place.

Please keep in mind that this is a preliminary forecast and could differ from our final forecast as more data comes in overnight and tomorrow morning.

June 07, 2026

Widespread Tornado Threat and Softball-Sized Hail Possible with Extreme Thunderstorm Risk on Sunday as Severe Weather Outbreak Enters its Second Day

June 07, 2026/ Alannah Campbell

After a busy day yesterday, that saw severe thunderstorms dropping massive baseball-sized hail over parts of Southeastern Saskatchewan and Southern Manitoba, we have the chance to do it all again today. It’s likely that today could be an even greater severe risk day than yesterday, with an extreme risk posed by the possibility of gigantic hail and multiple tornadoes. However, there has been a little bit of uncertainty surrounding how thunderstorms may end up developing this afternoon and evening.

Like yesterday, today’s severe thunderstorm threat will be triggered by a cold front that is currently oriented on a north-south axis and it located just west of the Saskatchewan/Manitoba border. This is a bit further west than originally anticipated when we issued our preliminary forecast on Friday, due in part to the front becoming stationary for a period of time yesterday. As a result, the severe risk today will cover more of Southeastern Saskatchewan and won’t extend as far east across Southern Manitoba.

To the east of the cold front, temperatures will once again climb into the low 30s this afternoon and it’s expected to be much more humid today, with dew points approaching the 20°C mark. The lack of moisture yesterday kept the cloud bases high, which greatly reduced the tornado risk, but it doesn’t look like that will be the case today.

The heat and humidity will lead to high levels of instability and upwards of 3000J/kg of CAPE to fuel thunderstorm development again today. Veering winds will also create a significant amount of shear to maintain large supercell thunderstorms.

***Surface weather map with the positions of highs, lows, and fronts displayed as of 6am cst this morning, courtesy of*** ***the national weather service***.

As we’ve mentioned in this forecast already, and in our forecast from yesterday, there was uncertainty with today’s severe thunderstorm risk. There have been some mostly non-severe thunderstorms that have tracked through Southern Manitoba already this morning and it is possible these could hinder additional development later today.

The storms have weakened over the past couple of hours and the thought was that if they manage to clear early enough, that will allow for there to be ample surface heating needed for the additional explosive development later. However, if the storms stuck around into the afternoon, the severe thunderstorm risk would be greatly reduced. With the clearing of these morning storms already occurring, it seems likely the severe threat will not be diminished.

The significant severe thunderstorms could develop in the late afternoon and into the early evening, around 4-6pm in Southeastern Saskatchewan and extending northeastward into Southern and Central Manitoba. These storms could once again explode into massive and dangerous supercell thunderstorms that would track roughly northeastward through the evening.

The area highlighted on our map in red, that covers a large portion of Southeastern Saskatchewan and Southwestern Manitoba, will be at a very high risk for dangerous severe thunderstorms. The area highlighted in purple, however, is where the strongest environment is expected to be and where there is an extreme risk for incredibly dangerous and life-threatening thunderstorms.

Throughout this region, the severe thunderstorms could end up producing absolutely massive, and maybe record-breaking, softball-sized hail, damaging wind gusts up to 120km/h, and very heavy rainfall that could lead to localized flooding. If we end up seeing the moisture that we were lacking yesterday, and the storm bases are lower, it is entirely possible that we could be looking at a tornado outbreak.

As we progress through the evening, more thunderstorms are expected develop and storms will also move into the region from south of the border. Once again, there is the likelihood that these additional storms will end up merging into a large line of storms which could impact a wide area into the overnight hours.

By the time we see a more linear storm mode, it’s likely that the storms will have weakened from their greatest strength, but they are still expected to be very strong and capable of producing very large hail, damaging wind gusts, and torrential rain.

The tornado threat should also decrease as we get later in the evening and into the overnight hours, but with how strong these thunderstorms could be today, there will still be a slight risk until the storms move into Northern Manitoba during the early morning.

Today’s severe weather threat is very serious. If you live in the area that we’ve highlighted in either red or purple on our map, PLEASE be prepared for the possibility of threatening weather to impact your area today. Make sure you have your phones charged and you have multiple ways to receive weather alerts. It’s also a good idea to have a plan in place in the event that you need to take shelter.

Once again, we will absolutely be live-streaming later so please join us while we monitor and track today’s severe weather. We hope everyone is able to stay safe today!

June 06, 2026

Tennis Ball-Sized Hail and Multiple Tornadoes Possible as Severe Thunderstorm Outbreak Targets Southeastern Saskatchewan on Saturday

June 06, 2026/ Alannah Campbell

Over the last several days, we’ve been closely watching the possibility of an intense multi-day setup for this weekend that would impact Southeastern Saskatchewan today and shift into Southwestern Manitoba tomorrow. There has been a lot of chatter online about this severe weather risk and combined with several high-profile storm chasers in the area from the US, it’s easy to say that we’re not looking at your average thunderstorm activity.

Today’s severe thunderstorm threat will be courtesy of a warm and cold front that is poised over Southeastern Saskatchewan and Southwestern Manitoba. The warm sector between the two fronts will see temperatures climb into the upper 20s and low 30s this afternoon, with high humidity.

This will lead to high levels of instability and CAPE (Convective Available Potential Energy) for thunderstorm development. Add in veering winds, changing direction with height, which will create a great amount of shear, and you have the recipe for an outbreak of significantly strong severe thunderstorms.

There have already been some scattered thunderstorms this morning which will continue through the afternoon across much of Southern Saskatchewan. These storms are expected to stay non-severe for the most part, but there is an isolated severe risk.

The thunderstorms that will be the focus for today aren’t expected to develop until this evening, starting around 5-6pm, to the east of Regina. Weather models are showing that these storms will likely quickly explode into large and dangerous supercell thunderstorms as they track roughly east-northeastward.

***Simulated reflectivity at 6pm CST, courtesy of weatherbell.***

The area highlighted on our map in red that covers a large portion of Southwestern Saskatchewan and into parts of the Parkland Region in Manitoba will be at the greatest risk for the strongest of these severe thunderstorms.

In this region, it’s likely that the storms could produce massive hail as large as tennis balls and possibly even larger, damaging wind gusts up to or exceeding 100km/h, and heavy downpours that could result in localized flooding. There is also a considerable threat that multiple tornadoes could touch down in this region; with the stretch from Weyburn to Yorkton appearing to be of particular concern.

As we progress through the evening, we will see additional thunderstorm development occur, which are expected to merge into a line of storms. This will bring a more widespread threat of the significant and strong storms across the rest of Southeastern Saskatchewan and into Manitoba.

***Simulated reflectivity at 8pm CST, courtesy of weatherbell.***

The severe weather threat will diminish gradually as the hours tick on in the evening and overnight. The tornado risk is also expected to decrease from its highest point by the mid-evening, but the storms could still be strong enough for the risk to remain through the evening. By midnight, there could still be a widespread risk of some severe storms, but this will quickly turn into a more isolated risk and scattered non-severe thunderstorms through the morning.

Looking ahead to tomorrow afternoon, we’re looking at another day of possibly strong severe thunderstorms, with the risk pushing further east across Southern Manitoba. What ends up happening tomorrow will really depend on how things unfold today. There’s the possibility that tomorrow could have even stronger storms than what is expected this afternoon, but this will be heavily contingent on how long any overnight storms manage to persist into tomorrow.

If the storms clear during the morning, that will allow for there to be ample surface heating for the development of another significant severe thunderstorm outbreak. However, if the storms continue into the afternoon, the severe thunderstorm risk will be greatly reduced.

We will have more details later today about how tomorrow could shape up. In the meantime, we will be watching today’s development very closely and we will be streaming later to track the severe thunderstorms live. Be sure to tune in!

May 19, 2026

Tornado Tuesday Could Bring Damaging Storms to Southern Ontario With Strong Severe Threat

May 19, 2026/ Brennen Perry

After an active, severe weather day on Monday that left widespread damage across parts of Central Ontario, especially throughout cottage country, another volatile day is shaping up across Southern Ontario.

In fact, Tuesday’s severe weather risk could end up being even stronger than Monday’s in some areas, particularly across Southwestern Ontario extending northeast toward Lake Simcoe and portions of the Golden Horseshoe.

Isolated thunderstorms are expected to develop during the late afternoon and early evening hours, bringing the potential for all modes of severe weather. This includes damaging wind gusts exceeding 100 km/h, hail up to ping pong ball size and the risk for a few tornadoes.

The primary area of concern stretches from Midland southwest toward Sarnia. Conditions in this corridor may support the development of supercells during the early stages of storm development. Supercells are rotating thunderstorms capable of producing tornadoes, very large hail and destructive wind gusts.

This early stage of the event is when the tornado and hail threat is expected to be at its highest, as storms remain isolated and are able to fully tap into the warm, unstable and highly sheared environment in place across the region.

As these storms track north and east through the evening hours, they are expected to gradually transition into a more linear storm mode. In other words, the isolated storms may begin to merge together into a squall line or broken line of embedded thunderstorms as they approach the Golden Horseshoe during the early evening.

At that point, the primary threat would shift away from tornadoes and large hail and toward widespread damaging wind gusts. However, isolated tornadoes can still occur within these types of storm lines through quick spin-ups along the leading edge, even if that is no longer the dominant concern.

The severe weather threat is expected to diminish fairly quickly after sunset, likely between 9 and 10 PM, as the loss of daytime heating weakens the atmosphere’s ability to sustain intense thunderstorms.

Behind the storms, a cold front is expected to sweep through the province overnight, bringing a sharp end to Southern Ontario’s first heat event of the year. By Wednesday morning, some areas could be waking up to temperatures back down in the single digits.

Based on the latest simulated radar data, isolated thunderstorms are expected to begin developing along a line extending from Midland southward toward Sarnia around 6 PM. However, that timing could still shift, especially since these setups can sometimes initiate earlier than forecast.

If storms are able to develop earlier in the afternoon, they would have access to an even more favourable environment, potentially increasing the severe weather risk.

Regardless of exactly when storms first form, the expectation is that they will remain fairly isolated for the first few hours of their lifespan as they track east of Lake Huron and northeast toward regions surrounding Lake Simcoe.

There is particular concern for the Midland to Kawartha Lakes corridor, where several model runs continue to indicate the potential for a dominant supercell to develop and track through the region.

Given that the strongest atmospheric conditions are expected to overlap in this area, any storm that develops there could become quite intense quickly, with the potential for tornadoes and very large hail.

Additional severe thunderstorms may also develop farther southwest and track through areas including London, Kitchener, Orangeville and Barrie during the dinner hour.

Farther east, a few isolated storms may also develop near Bancroft and the Ottawa Valley. However, the environment in those areas does not currently appear to be quite as favourable for widespread severe weather, so confidence in storm intensity there remains lower.

As the evening progresses and daylight fades, the isolated cells are expected to begin merging together into a more organized line of storms while gradually weakening as they approach the Greater Toronto Area.

These storms could certainly remain severe into the evening hours, but the primary threat would likely transition toward damaging wind gusts, which is common with linear storm events.

That does not mean the tornado threat disappears entirely though. An isolated QLCS tornado cannot be ruled out within the line as it tracks eastward through the evening.

QLCS stands for “quasi-linear convective system,” which is essentially a line of thunderstorms capable of producing brief, fast-forming tornadoes embedded within the line itself. These tornadoes are often difficult to detect and can develop with little warning.

The hail threat, however, is expected to decrease significantly by this stage of the event as storms lose their isolated structure and strong updrafts.

Overall, the severe weather risk should come to a fairly quick end shortly after sunset as the atmosphere stabilizes. While a few overnight thunderstorms may linger behind the main line, they are expected to remain below severe limits.

**ESTIMATED TEMPERATURE (°C)** - MAP FROM WEATHERBELL

Looking ahead to the rest of the week, Southern Ontario’s brief taste of summer-like weather is set to come to an abrupt end behind Tuesday night’s cold front.

Temperatures are expected to tumble overnight, with some parts of Southwestern and Central Ontario potentially waking up to single-digit temperatures by Wednesday morning. In fact, there may even be some frost risk later this week across portions of Central Ontario as cooler air settles back into the province.

May 18, 2026

Multi-Day Severe Storm and Tornado Risk Targets Southern Ontario Alongside Summer-Like Heat

May 18, 2026/ Brennen Perry

Southern Ontario is about to get its first real taste of summer weather in 2026, and it’s arriving with a potentially stormy side effect.

Temperatures are expected to soar into the upper 20s and even near 30°C in some areas on both Monday and Tuesday as a surge of warm and humid air spreads across the province. While this early-season heatwave will be relatively brief, it’s expected to create a volatile atmosphere capable of producing two consecutive days of severe thunderstorms across parts of Southern Ontario.

From large hail and damaging wind gusts to the possibility of isolated tornadoes, there’s a lot to track over the next 48 hours. Our team will be providing extensive live coverage throughout both severe weather risks on our YouTube channel, with real-time storm tracking, warning updates, radar analysis and live storm chasing coverage as storms develop. If you’re looking for in-depth storm coverage in Ontario, Instant Weather will be the place to be over the next two days.

The first round of potentially severe weather is expected to develop during the mid to late afternoon hours on Monday as strong storms over Michigan begin to track into the Lake Huron and Manitoulin Island area around 3-6 PM. These storms are likely to merge into a single line with embedded cells as they cross the Bruce Peninsula and into regions around the northern and eastern shoreline of Georgian Bay. Early in their lifespan, they could present all storm hazards, including damaging wind gusts and hail up to the size of toonies.

As these storms move into Central Ontario, including much of Ontario’s cottage country such as Muskoka, North Bay and Algonquin Park, the environment could become capable of supporting a brief spin-up tornado. There is still some uncertainty regarding the tornado risk as some models suggest the storms may arrive later in the evening, after the most favourable tornado environment begins to weaken.

A secondary cluster of storms may also approach regions further south and west, including Deep Southwestern Ontario and along the eastern Lake Huron shoreline during the late afternoon and early evening hours. At this point, damaging wind gusts appear to be the primary threat in these areas, while the hail and tornado risk looks lower, although it can never be completely ruled out.

As these clusters of storms track northeast, they are expected to gradually weaken by the late evening as the daytime heating fuelling them begins to fade away. Due to this, there remains some uncertainty regarding how far east the severe risk will extend, as it will largely depend on how quickly the storms move before losing access to the strongest instability.

We have gone with a slight (level 2 out of 5) severe thunderstorm risk for locations including Windsor, Leamington, Chatham, Sarnia, Grand Bend, Goderich, Kincardine, Hanover, Owen Sound, Wiarton, Tobermory, Collingwood, Midland, Bracebridge, Huntsville, Parry Sound, Britt, Manitoulin Island, Sudbury, North Bay, Algonquin Park and Deep River. This is the area most likely to experience the strongest storms today, but it’s important to remember that not everyone within the risk zone will necessarily see severe weather.

A marginal (level 1 out of 5) severe thunderstorm risk includes London, St. Thomas, Woodstock, Tillsonburg, Brantford, Kitchener, Guelph, Orangeville, Barrie, Orillia, Bancroft, Pembroke and Renfrew. If severe weather develops in these areas, it will most likely be isolated damaging wind gusts associated with weakening storms during the evening hours.

Non-severe thunderstorms are also possible for the Greater Toronto Area and parts of Eastern Ontario. While widespread severe weather is not expected there at this time, any storms that do develop could still produce frequent lightning, heavy downpours and locally gusty winds.

Turning towards Tuesday, the overall severe weather setup may become even more favourable and widespread, but confidence in storm development itself remains lower.

A very warm and unstable atmosphere is expected to build across Southern Ontario throughout the afternoon and evening hours. If storms are able to form, they could rapidly intensify and become severe across Southwestern Ontario, the Golden Horseshoe and areas surrounding Lake Simcoe, along with Central and Eastern Ontario. This setup would support all severe weather hazards, including damaging wind gusts, large hail and isolated tornadoes.

However, forecast models continue to struggle with exactly where storms will initiate and whether they will develop at all. That uncertainty is preventing a more aggressive severe weather outlook at this time.

Current indications suggest isolated thunderstorms may first begin developing around Grey-Bruce during the mid-afternoon hours before slowly tracking southeast toward regions around Lake Simcoe between roughly 2-5 PM. Additional thunderstorm development may also occur farther southwest and along the Lake Erie shoreline later in the day.

Like Monday, these storms will be heavily dependent on daytime heating and atmospheric instability. Once the sun begins to set around 8-9 PM, any storms that have developed are expected to gradually weaken fairly quickly.

At this time, it appears the Ottawa Valley may remain outside the main severe weather risk on Tuesday. However, that could still change in our final outlook as confidence increases regarding storm development and storm coverage. The atmosphere across Eastern Ontario will still be somewhat supportive of marginally severe thunderstorms, but confidence is currently not high enough to formally include those regions within the isolated severe risk area.

June 27, 2025

Southern Ontario Faces Widespread Severe Threat Including Damaging Wind Gusts, Toonie-Sized Hail & Tornado Risk on Friday

June 27, 2025/ Brennen Perry

After Southern Ontario experienced some severe weather last weekend along with our first significant heat wave of the season, things have quieted down over the past few days. Milder air brought temperatures back to seasonal values on Wednesday and Thursday.

However, it looks like we’re about to heat up again heading into the weekend. The good news is, it won’t be anywhere near the oppressive heat we saw earlier this week.

In addition to the return of summer warmth, there’s a growing risk of widespread severe storms on Friday. This threat covers much of Southwestern Ontario and stretches into parts of Central Ontario and the Golden Horseshoe.

Isolated thunderstorms are expected to fire up over Lake Huron and move into a very unstable environment during the afternoon, leading to the possibility of all severe weather hazards. This includes damaging wind gusts, large hail and potentially even one or two tornadoes.

As these storms push eastward into the evening hours, there’s a chance they could merge into one larger cluster of storms. This line may reach portions of the Greater Toronto Area and bring a continued threat of damaging winds, small hail and localized flash flooding.

**ESTIMATED DAYTIME HIGH in °C** - MAP FROM WEATHERBELL

While the heat has pulled back across much of Southern Ontario over the past few days (except for Deep Southwestern Ontario), we’re expecting it to return on Friday. Areas south of Lake Simcoe will likely see daytime highs climb back into the upper 20s and even low to mid-30s across parts of Southwestern Ontario.

This won’t be the same level of heat we saw earlier in the week, but it will be a noticeable jump compared to the cooler air on Thursday that kept many places under 20°C for most of the day.

Once you factor in the humidity, some parts of Deep Southwestern Ontario could be feeling close to the upper 30s again.

As we often see on days with elevated storm risk, the morning could bring some scattered showers or thunderstorms near Lake Huron and Georgian Bay. These are not expected to be severe, but they will play an important role in shaping the setup for later in the day.

If the morning rain and storms linger longer than expected, they could limit afternoon storm development by preventing the atmosphere from fully recovering. This could reduce the strength or delay the timing of any severe storms into the evening when conditions aren’t quite as favourable.

There’s also some disagreement in the forecast models about how far south this morning precipitation might extend, especially in the zone where the severe risk is currently expected to be the highest.

If the atmosphere is able to recover in time, we could see isolated storms begin to fire over Lake Huron as early as mid-afternoon (2 to 4 PM), then track inland toward Grey, Bruce and Huron counties.

There’s still some uncertainty on the exact placement of this development. Storms could form anywhere along a corridor stretching from Manitoulin Island all the way down to Sarnia.

**ESTIMATED ENVIRONMENT FOR TORNADOES** - MAP FROM WEATHERBELL

As these cells develop over Lake Huron, they’ll be moving into a rapidly strengthening environment. Current model data suggests the highest tornado potential may be from Goderich to Owen Sound around 3-5 PM.

This region could see the greatest risk for severe weather during the mid to late afternoon hours. Storms that remain isolated early on may evolve into supercells capable of producing damaging wind gusts, large hail and a tornado or two.

While this particular setup leans more toward Southwestern Ontario, other models point to a similarly strong environment farther northeast into Central Ontario. This includes areas around Lake Simcoe, as well as parts of Simcoe County, Muskoka and the Kawartha Lakes.

As the storms push eastward during the late afternoon, current data suggests they may merge into one larger cluster of storms by the time they reach Central Ontario and then move into the Greater Toronto Area during the early evening.

At that point, the tornado threat will decrease, but the risk of damaging winds will become the dominant threat. This is typical when storms evolve into more linear systems.

Flash flooding could also become a major concern, especially in urban areas like the GTA, which are more prone to poor drainage. Some forecast models even suggest that this line could stall or ‘train’ over the same area, which would bring the potential for very heavy rainfall in a short amount of time.

The overall severe threat should begin to wind down between 9 and 10 PM as the sun sets and daytime heating fades. That said, the storm cluster may continue eastward into the Niagara Region and parts of Eastern Ontario overnight, though it’s expected to be non-severe by then.

As mentioned, the highest severe threat will likely be in the mid to late afternoon over Southwestern Ontario, especially as storms come ashore from Lake Huron.

These storms could bring damaging wind gusts, hail up to the size of toonies and possibly one or two tornadoes. The tornado risk would be greatest shortly after the storms reach land and should taper off farther inland.

Deep Southwestern Ontario might also see a few isolated storms develop during the afternoon, though the environment doesn’t look quite as favourable compared to areas farther north.

Still, any storms that do form here could bring isolated damaging wind gusts, quarter-sized hail and even a low-end tornado risk that can’t be ruled out.

As the storms move into Central Ontario later in the day, the primary risk will transition to damaging winds. The threat of hail and tornadoes will decrease, but a few storms could still produce quarter-sized hail and, again, an isolated tornado remains possible.

There’s also the potential for some isolated development around Georgian Bay and Lake Simcoe in the afternoon. If that happens, it could boost the tornado and hail risk across that region.

By the time the line of storms reaches the Golden Horseshoe, it will likely be starting to weaken. However, it could still bring the potential for isolated wind damage, nickel-sized hail and maybe a brief tornado, though that risk becomes increasingly unlikely at that point.

June 21, 2025

Southern Ontario to Kick Off Summer This Weekend With Significant Severe Risk and Tornado Threat on Saturday; Sizzling Heat Near 40°C on Sunday

June 21, 2025/ Brennen Perry

Summer officially arrived late Friday night with the summer solstice, and it looks like Mother Nature isn’t wasting any time making it feel like summer across Southern Ontario. A multi-day heat wave is on the way, bringing the potential for record-breaking temperatures starting Sunday and continuing into early next week.

But before the heat sets in, we’re looking at what could easily be our strongest and most widespread severe weather threat of the season so far on Saturday. There are a lot of factors at play that make this a classic ‘boom or bust’ setup, which we’ll break down below.

There’s high confidence in a potent storm environment stretching across much of Southern Ontario. The big wildcard, however, is whether storms will actually develop to take advantage of all that energy. If they do, they could bring very large hail, destructive wind gusts, and possibly even a couple of tornadoes.

What’s especially concerning is that the storm environment doesn’t fade away after sunset like it typically does. In fact, it remains quite strong through the overnight and into Sunday morning, which could support a nocturnal line of storms with widespread damaging wind potential.

Once the severe risk passes, intense heat begins to build. Temperatures will soar well into the 30s by Sunday, with humidex values making it feel closer to the 40s. The heat continues Monday and Tuesday, with some relief expected midweek. That said, it’ll likely stay warm into the end of June and possibly early July.

A key ingredient in Saturday’s severe weather threat is already unfolding over North Dakota early Saturday morning. An intense line of storms, known as a “derecho” (a fast-moving complex of severe thunderstorms that can produce widespread wind damage), is sweeping through the northern Plains.

This system is producing destructive wind gusts of over 150 km/h along with several tornadoes and has already left damage in its wake. It’s expected to continue tracking eastward into the Great Lakes region through the day.

So what does that mean for Southern Ontario?

Derechos are known to travel long distances, and current model guidance suggests this one could follow a path toward Northeastern Ontario. Areas near the U.S. border, including Sault Ste. Marie and Elliot Lake, could be affected by the remnants of this system Sunday morning.

There’s still some uncertainty around how strong the system will be by the time it reaches Ontario. Forecast models often struggle with capturing the evolution and intensity of derechos, so the possibility that this one is being underestimated shouldn’t be ignored.

The projected track of what’s left of this potentially decaying derecho places it crossing Lake Huron and Georgian Bay into Central Ontario sometime Saturday afternoon.

If it maintains strength, it could bring damaging wind gusts, hail up to the size of toonies and maybe even an isolated tornado. But this could just be the first of multiple storm rounds.

Some models are also hinting at additional isolated storm development around Elliot Lake and Sudbury in the wake of the earlier line. That suggests the atmosphere could quickly recharge, although it’s still unclear how widespread any new storms would be.

As we move into the late afternoon and evening hours on Saturday, the storm environment really ramps up. One of the key indicators we look at, the Significant Tornado Parameter, is literally off the charts in some areas, particularly near the Lake Huron shoreline and into Georgian Bay.

Here’s the catch, though: storms need to develop in this environment to take advantage of it. If they do, they could rapidly become severe, with the potential for all hazards. That includes large hail (possibly golf ball-sized or bigger), destructive winds over 100 km/h, and tornadoes.

Looking at what one model is simulating, there’s a notable lack of storms in the highest risk areas around Lake Huron. Instead, storms appear to fire up along a line from Sudbury to Parry Sound through Muskoka, just northeast of the most primed environment. These storms could still be strong and bring similar hazards.

It’s worth noting that models may be underdoing storm development in Southwestern Ontario. That’s something we’ll need to monitor in real time. If nothing happens in Southwestern Ontario, it could end up being a ‘bust’ - which would be good news for those who aren’t fans of severe storms.

Typically, severe weather threats wind down after sunset as daytime heating fades. But in this case, models are suggesting the environment will remain unusually supportive of storm activity well into the overnight hours and early Sunday.

There’s even the potential that a new line of storms forms north of Georgian Bay and sweeps southeast through Southern Ontario overnight. If this happens, it could evolve into another derecho-type system - similar to the one seen Friday night in North Dakota.

Forecasting derechos is notoriously difficult, as models often fail to capture their full strength and endurance. While nothing is certain, this setup definitely has the ingredients to support a nocturnal derecho-type event.

If this scenario plays out, we could see widespread wind damage across Central and Eastern Ontario, possibly extending into parts of Southwestern Ontario and the Golden Horseshoe.

This is a very tricky forecast, and while we've gone with a ‘significant’ (level 4 out of 5) risk, that doesn’t mean everyone will see storms. The risk will come in waves, and some areas may be completely missed.

That said, the potential severity of any storms that do form justifies this level of concern. We’re talking about the possibility of golf ball-sized hail or larger, destructive wind gusts (possibly from a derecho), and a few tornadoes. The tornado risk will largely depend on storm structure—more linear setups will favour damaging wind, while discrete supercells could increase the tornado threat.

The highest severe risk covers areas around Georgian Bay including Sault Ste. Marie, Elliot Lake, Manitoulin Island, Britt, and into Central Ontario such as Muskoka, Simcoe County and Bancroft.

A broader ‘strong’ risk zone includes much of Central and Eastern Ontario, the northern portions of Southwestern Ontario, and the Greater Toronto Area.

Meanwhile, areas like London, Kitchener, Hamilton and the Niagara region fall into the widespread severe risk category.

For once, Deep Southwestern Ontario may dodge the worst of the storms. Windsor, Chatham and Sarnia are currently in the isolated severe risk zone. While a stray storm can’t be ruled out, most of that region looks to stay quiet Saturday.

There may be another round of severe weather on Sunday afternoon and evening, but confidence in the details is still low. Eastern Ontario may be favoured, but we’ll refine that forecast once Saturday plays out.

Sunday marks the beginning of an extended stretch of dangerously hot temperatures. The most intense heat is expected across Deep Southwestern Ontario into the Golden Horseshoe.

Areas like Windsor, Sarnia, London, Hamilton, Kitchener and Toronto could see daytime highs between 35°C and 40°C. With humidity, it will feel like the mid-40s in many spots.

Locations near Lake Ontario, Lake Erie, Lake Huron and Georgian Bay will be 5 to 10 degrees cooler, but it doesn’t take much distance inland to hit the oppressive heat.

Elsewhere in Southern Ontario, expect highs in the low to mid-30s with humidex values near 40°C.

Heat Safety Tips:

Stay hydrated and avoid strenuous outdoor activity during peak heat hours.
Check in on vulnerable individuals, including the elderly, young children and those with health conditions.
Never leave pets or people in parked vehicles.
Use fans or air conditioning when possible and find shade or cooling centres if needed.

There’s a good chance many locations will break temperature records going as far back as the 1800s over the next few days.

According to Environment Canada, record highs in cities like Toronto, Windsor, Ottawa, London and Hamilton are in the mid to upper 30s for Sunday, Monday and Tuesday. Based on the current forecast, some of these records may fall.

Monday brings more of the same, with extreme heat expanding into parts of Central and Eastern Ontario in addition to Southwestern Ontario and the GTA.

Once again, humidex values will push into the 40s, making it feel extremely uncomfortable and even dangerous for some.

Tuesday will still be hot, but may be slightly cooler compared to Monday. Some relief is on the way by Wednesday, although temperatures will likely stay warm overall.

June 18, 2025

Severe Storms Target Southwestern Ontario Wednesday with Tornado and Damaging Wind Risk

June 18, 2025/ Brennen Perry

Storm season has certainly gotten off to a slow start in Southern Ontario, to say the least. Aside from a few scattered events earlier in the spring, it’s been a fairly quiet lead-up to summer across the region.

However, that’s about to change in a big way. As we approach the summer solstice on Friday, which marks the official start of summer, the pattern is shifting. Warmer temperatures and a more active storm pattern are setting the stage for what looks like a much stormier stretch of weather.

Wednesday’s setup will feature an environment that becomes increasingly favourable for storm development through the day. The main focus will be across Southwestern Ontario and into parts of the Golden Horseshoe during the afternoon and evening hours.

While the storms will likely start off isolated and scattered, they are likely to move quite slowly. This raises the potential for localized flooding, especially in areas that see multiple rounds of heavy rainfall from training storms.

A few storms could also produce near-severe wind gusts and small hail, particularly during the late afternoon and early evening. While not every area will be affected, those that are could see some very heavy rainfall over a short period of time.

The greater concern comes later in the day for Deep Southwestern Ontario, where a more potent setup could take shape.

Storms are expected to develop over Michigan during the afternoon and early evening. As these storms intensify, they may track eastward and cross into Ontario during the evening. Areas such as Windsor, Chatham, and Sarnia could be in the path of these stronger cells.

These storms will be moving into a more unstable environment that could support damaging wind gusts, quarter-sized hail, and potentially even an isolated tornado.

While confidence in storm development across the border is high, the extent of the severe threat in Ontario will depend heavily on the exact timing of when those storms cross into the province.

**ESTIMATED AIR TEMPERATURE** - MAP FROM WEATHERBELL

Before the storms arrive, temperatures will be on the rise across much of Southern Ontario. Afternoon highs are expected to reach the mid to upper 20s across Southwestern Ontario and into the Golden Horseshoe by early afternoon.

Central and Eastern Ontario will be a bit cooler, with highs ranging from the low to mid-20s. The Ottawa Valley could end up a touch warmer than the surrounding areas.

This heat and humidity will act as fuel for thunderstorm development, especially around Lake Huron and into areas near Lake Simcoe by the afternoon. Models vary on how widespread storm activity will be, with some showing scattered pop-up storms and others hinting at a more organized cluster.

Either way, any storms that do develop will be slow-moving, and locations underneath these cells could see multiple rounds of rainfall. That’s where the flood threat becomes more concerning, especially in urban areas that are more prone to flash flooding.

For much of the region, flooding will remain the primary concern. However, a few stronger storms could bring near-severe wind gusts and hail up to nickel size.

By the evening, our attention will turn stateside, where strong to severe storms are expected to organize over Michigan.

These storms are forecast to cross into Deep Southwestern Ontario sometime during the evening. The atmospheric setup in that region will support damaging wind gusts, hail up to the size of quarters, and the potential for a tornado.

Again, the timing will be critical. If these storms arrive before sunset, they’ll have access to better instability and surface heating, making them more capable of becoming severe. However, if they hold off until later in the night, the lack of daylight heating could limit their intensity.

Models are currently showing a narrow window between 6 and 9 PM where the tornado potential could materialize, particularly around Windsor, Leamington, and Chatham. This will depend on how quickly storms move eastward from Michigan and whether they interact with the more favourable environment before it begins to weaken.

Once the sun sets, the tornado threat should diminish quickly, though some thunderstorm activity may continue through the night into early Thursday morning.

While a few non-severe thunderstorms may linger overnight, the severe threat will likely taper off before midnight.

As it stands, the highest risk for severe weather on Wednesday will be focused on Deep Southwestern Ontario, including Windsor, Leamington, Chatham, and Sarnia, with the window for impactful storms likely between 3 PM and midnight.

We’ve placed this region under a Level 2 (Widespread) risk due to the potential for damaging wind gusts and one or two tornadoes. Up to quarter-sized hail and locally up ot 50-100mm of rain is also possible.

Elsewhere across Southwestern Ontario and into the Golden Horseshoe, we’ve gone with a Level 1 (Isolated) risk.

This lower tier is mainly for flooding concerns, as slow-moving storms could drop significant rainfall over the same areas during the afternoon and early evening.

Some locations could also see isolated severe wind gusts, nickel-sized hail, and a very low tornado risk (confined mainly to parts of Southwestern Ontario).

June 01, 2025

Two EF1 Tornadoes Confirmed Northeast of Edmonton From Monday, May 26th, 2025

June 01, 2025/ Brennen Perry

***NOTE: YOU CAN CLICK ON THE IMAGE TO OPEN A ZOOMABLE VERSION***

Two EF1 tornadoes have been confirmed in Alberta from May 26th, 2025 by the Northern Tornadoes Project (NTP). Thankfully, there were no injuries with these two tornadoes. The strongest of the two was on the ground for an impressive 21.2km and had estimated wind speeds of 175km/h. The two tornadoes touched down near Lac la Biche and left behind lengthy, narrow paths of damage, including a partially removed roof from a home and numerous snapped and uprooted trees.

Investigators from the NTP conducted thorough ground and drone surveys on May 28th and noted that Alannah and Patricia from our own Instant Weather team helped get their team deployed quickly. The NTP wrote: “Thanks to Alannah and Patricia at Instant Weather for their initial (late-night) alert to the damage, allowing us to get our team out faster!” We at IW are grateful that we were able to help NTP with their investigation and super thankful that no one was injured in these two tornadoes. The NTP meticulously documented the aftermath and their findings paint a clear picture of the two separate twisters that tore through the region.

The Atmore Twister – A Lengthy Path of Damage

The first tornado, designated the "Atmore" event, began its destructive journey at approximately 7:00 PM MDT (0100 UTC) on May 26th.

Final EF-Scale Rating: EF1

Estimated Max. Wind Speed: 175 km/h

Track Length: A substantial 21.2 km

Max. Path Width: 300 m

Motion: From the Southwest (approx. 220 degrees)

This twister carved a significant path, causing notable damage to homes near Atmore and Rossian (north of Plamondon). Reports detailed structural impacts and the NTP survey confirmed these, along with extensive tree damage. Satellite imagery review also highlighted the visible tree damage along its long, narrow track. Luckily, despite the substantial property damage, no injuries were reported.

The Avenir Tornado – A Shorter, Wider Impact

Just 25 minutes after the Atmore tornado began, a second EF1, named the "Avenir" event, touched down further to the northeast at approximately 7:25 PM MDT (0125 UTC).

Final EF-Scale Rating: EF1
Estimated Max. Wind Speed: 150 km/h
Track Length: 6.43 km
Max. Path Width: A slightly wider 370 m
Motion: From the South-Southwest (approx. 205 degrees)

While shorter in track length, the Avenir tornado left a clear signature, primarily impacting forested areas near the community of Avenir. Satellite imagery initially revealed its narrow path of tree damage, which was later confirmed and documented by the NTP's ground and drone survey. As with the Atmore event, no injuries were reported in connection with this tornado.

Understanding the Findings

The Northern Tornadoes Project plays a crucial role in confirming, classifying and analyzing tornado damage across Canada. Their use of satellite imagery, followed by on-the-ground surveys with drones, allows for precise classification and understanding of these powerful weather phenomena.

These EF1 tornadoes, with wind speeds reaching up to 175 km/h, serve as a reminder of the potential for severe weather in Alberta. While not the most powerful on the Enhanced Fujita (EF) Scale, they are certainly capable of causing significant localized damage, as evidenced by the events near Lac la Biche.

Find out more & get notified

You can view precise tracks of these tornadoes and explore other Canadian tornado and downburst events on the interactive NTP Dashboard.
Always have a plan for severe weather and download our free app Instant Weather to get notified of any alerts from Environment Canada or any custom updates from the IW team regarding rotation, funnel cloud reports, etc.

May 21, 2025

Ontario’s First Confirmed Tornado of 2025: EF0 Touches Down Near Woodstock Last Week

May 21, 2025/ Brennen Perry

Ontario’s tornado season has officially begun. The first confirmed tornado of 2025 touched down during the early morning hours of May 16th, just south of Lakeside, Ontario, northwest of Woodstock.

The tornado developed along the leading edge of a line of storms that had tracked into the province from Michigan.

While this EF0 tornado near Lakeside was the first confirmed in Ontario this year, it wasn’t the first in Canada.

According to the Northern Tornadoes Project, this brings Canada’s confirmed tornado count for 2025 to five.

The season began with an EF0 tornado in Alberta in early April, followed by an EF1 in Quebec later that month. Just one day before the Lakeside event, two EF0 tornadoes were confirmed in Manitoba on May 15th.

With peak season still ahead, this serves as a timely reminder that severe weather can happen quickly and under conditions that don’t always look extreme on the surface.

Even low-end risks deserve attention, especially when storms arrive at night, when people are less likely to be tuned in.

The Tornado: A Narrow but Confirmed Touchdown Near Lakeside

**Survey map for the Lakeside EF0 tornado** (source: Northern Tornadoes Project)

According to the Northern Tornadoes Project (NTP), the tornado developed just south of the village of Lakeside, approximately 25 km northwest of Woodstock. It touched down around 3:00 AM EDT, shortly after a squall line of thunderstorms entered the region from the west.

**Drone photo of worst damage point featuring multiple snapped conifers** (source: Northern Tornadoes Project)

Damage was limited to trees and a power pole, with no injuries reported. The tornado was assessed as an EF0, with estimated maximum wind speeds of 115 km/h. It travelled a distance of 3.6 km, with a maximum path width of 160 metres, moving generally from the west-southwest (255°).

**Radar data shows possible rotation near lakeside** (source: iw pro)

Radar imagery at the time showed a compact area of low-level rotation, but due to the storm’s embedded structure and the overnight timing, the event went unwitnessed until damage was reported later that day.

The NTP conducted both ground and drone surveys on May 20th to confirm the tornado’s track and intensity.

This information is sourced from the Northern Tornadoes Project’s full report, which can be found here.

**Survey map showing the location of the EF0 downburst (black oval) and collected data** (source: Northern Tornadoes Project)

In addition to the confirmed tornado near Lakeside, the Northern Tornadoes Project also verified a separate EF0 downburst near Chatham from the same storm system.

The downburst occurred around 2:15 AM EDT, roughly 45 minutes before the tornado, and caused significant damage to several barns, farm buildings, power poles, and trees.

While similar wind damage was reported across parts of Southwestern Ontario—from Windsor to Shrewsbury—only the enhanced damage south of Chatham was surveyed.

Wind speeds were estimated to have peaked at 130 km/h, placing the event at the high end of the EF0 scale. No injuries were reported.

Timeline: Forecast Leading Up to the Tornado

Forecast models began flagging the potential for severe storms several days in advance, particularly in Deep Southwestern Ontario, where the environment appeared favourable for severe weather.

Instant Weather and the U.S. Storm Prediction Center both noted the possibility of tornadoes — albeit marginal — due to the timing and nocturnal nature of the storms. This provided over 24 hours of advance notice about the potential for severe weather.

Despite the lower-end risk, one storm managed to spin up a brief EF0 tornado shortly after 3:00 AM on May 16th.

Instant Weather first highlighted the tornado potential on Wednesday afternoon, referencing the Storm Prediction Center’s forecast and the setup in Michigan and Southwestern Ontario:

#ONStorm #ONwx ⚠️ SEVERE STORM RISK - LATE THURSDAY

Heads up! We’re closely watching the potential for strong storms late Thursday evening into the early morning hours of Friday.

Right now, the highest risk appears to be in Deep Southwestern Ontario—including Windsor, Chatham,… pic.twitter.com/SWU0hV7TAx
— Instant Weather Ontario ⛈️ (@IWeatherON) May 14, 2025

The following morning, just under 24 hours before the confirmed tornado, Instant Weather once again flagged the risk.

This time, the post specifically mentioned that a 2% tornado risk extended into Sarnia, Chatham, Grand Bend, and as far northeast as London, placing the affected area firmly within the broader risk zone:

#ONStorm #ONwx 🌪️ Tornado Thursday for Deep Southwestern Ontario?

The Storm Prediction Center (SPC) has just updated their severe weather outlook—and it now includes a more substantial tornado risk extending into the Windsor area.

They’ve upgraded the region around Windsor to a… pic.twitter.com/XglBkvJxBp
— Instant Weather Ontario ⛈️ (@IWeatherON) May 15, 2025

Later Thursday afternoon, a forecast was issued by Instant Weather calling for the potential of isolated tornadoes overnight. The forecast map outlined a marginal risk that included the area near Lakeside, where the tornado would eventually touch down:

#ONStorm #ONwx ⛈️💨 Nocturnal Thunderstorm Threat With Damaging Wind Gusts and Isolated Tornado Risk for Southwestern Ontario Tonight

📅 Thursday, May 15 - Friday, May 16, 2025

⤵️ VIEW THE FULL FORECAST:https://t.co/Pu0YPOAAVu

- Brennen pic.twitter.com/KYtjPY2hxR
— Instant Weather Ontario ⛈️ (@IWeatherON) May 15, 2025

Around 1:47 AM, just over an hour before the tornado touched down, Instant Weather sent out a custom notification for the London area, referencing minor rotation and clearly stating that “an isolated tornado cannot be ruled out”:

At 2:55 AM, Environment Canada issued a Severe Thunderstorm Warning, which included a note that severe thunderstorms can produce tornadoes. This came approximately five minutes before the tornado would touch down near Lakeside

Finally, live coverage was underway on Instant Weather’s YouTube channel during the time the tornado developed around 3:00 AM, as the storm moved through Oxford County.

May 15, 2025

Nocturnal Thunderstorm Threat With Damaging Wind Gusts and Isolated Tornado Risk for Southwestern Ontario Tonight

May 15, 2025/ Brennen Perry

updated map - 10:50 PM (CLICK HERE FOR THE PREVIOUS MAP)
***NOTE: YOU CAN CLICK ON THE MAP TO OPEN A ZOOMABLE IMAGE***

UPDATE (10:50 PM):

We’ve been closely tracking the line of storms developing across Michigan, and it’s now set to move into Deep Southwestern Ontario over the next few hours.

Based on the latest model data, current environmental conditions, and how well the storm is holding together despite the lack of daylight heating, we believe there’s enough evidence to upgrade parts of Deep Southwestern Ontario to a ‘strong’ (3/5) risk—mainly due to the potential for intense wind gusts.

Large hail up to the size of toonies is also possible, and we can’t completely rule out an isolated tornado.

We’ve also extended the ‘slight’ (2/5) risk further inland to include areas like Goderich and London, as new data suggests the line could stay fairly strong as it tracks deeper into Southwestern Ontario during the pre-dawn hours. Again, damaging wind gusts remain the primary threat.

The line is expected to cross the border just after midnight, with the severe threat gradually tapering off but still continuing until around 3–4 AM.

ORIGINAL FORECAST

While storm season has had a quiet start in Southern Ontario, things are beginning to ramp up with a late-night storm risk expected between Thursday evening and early Friday morning. A strong line of storms is forecast to form across Michigan late tonight, initially beginning as discrete supercells over parts of Wisconsin and Illinois.

Based on the latest guidance, these storms are expected to organize into a more linear structure as they track eastward, eventually crossing into Southwestern Ontario sometime just after midnight. While they’ll likely lose some of their strength after dark, especially without daytime heating, the atmosphere may still be supportive enough for them to maintain some intensity as they move into our region.

That said, there’s still a fair amount of uncertainty about just how strong this line will be once it crosses the border, and how quickly it might weaken as it tracks northeast through the early morning hours of Friday.

The biggest concern with this system is the potential for damaging wind gusts. This squall line will stretch from the Upper Peninsula of Michigan all the way down through Ohio as it enters Ontario, which could lead to widespread impacts. Areas from the Bruce Peninsula all the way down to Deep Southwestern Ontario are at risk of strong winds embedded within the line.

The highest risk appears to be in Deep Southwestern Ontario, where the line will first cross into Ontario. Regions like Windsor, Leamington, Chatham, and Sarnia are most likely to experience the strongest part of this line. While damaging wind gusts are the main hazard, we also can’t completely rule out the chance for hail and even a brief tornado, especially if the storms arrive a bit earlier than forecast.

Hail up to the size of quarters is possible, and while the tornado risk is considered low overall, it does exist. The biggest concern here is that this is a nocturnal threat. If a tornado were to develop overnight, it would be harder to spot and could be rain-wrapped, making it even more dangerous. That’s why it’s so important to stay alert and have a way to receive warnings while you sleep.

Storm development will begin with discrete cells over Wisconsin and Illinois, likely forming into a long line around 8–10 PM near Chicago and across Lake Michigan.

The timing of this formation is crucial. If the line develops sooner and sweeps across Michigan quickly, it could result in a more robust severe risk for Deep Southwestern Ontario, where the environment is more favourable before midnight.

No matter the timing, damaging winds remain the most likely outcome with this type of linear storm setup.

As of now, future radar models suggest the storms will cross into Ontario between 1 and 2 AM, hitting areas like Windsor and Sarnia first before stretching further northeast. However, there’s still wiggle room in this timing. It could arrive earlier and stronger, or later and already weakening before reaching our region.

**ESTIMATED TORNADO ENVIRONMENT** - MAP FROM WEATHERBELL

While widespread wind damage is the primary concern tonight, there is some minor tornado potential—especially in Essex County just after midnight. Again, the odds are low, but not zero.

Because of the overnight timing, it's extra important to have notifications enabled on your phone or weather radio. Make sure you have a way to receive alerts while you're asleep in case a warning is issued. Our free app is a great way to instantly get Environment Canada alerts, along with our custom notifications issued for your exact location.

The line of storms is expected to continue northeast through the early morning hours, bringing heavy rain, gusty winds, and frequent lightning to much of Southwestern Ontario and parts of the Greater Toronto Area between 3 and 6 AM.

While the line should gradually weaken during this time, it could still pack a punch in some localized areas. There’s some uncertainty around how long it will be able to hold its strength since the atmospheric environment in Ontario is notably weaker than what the storms had access to in the U.S.

Latest model runs show the system likely fizzles out once it reaches Lake Simcoe, meaning Eastern and Central Ontario probably won’t see much beyond a few scattered morning showers or storms.

Another round of storms is possible Friday afternoon and evening, particularly for Eastern Ontario and parts of Deep Southwestern Ontario. We’ll have more details on that in a separate update.

As it stands, the highest storm risk tonight is in Deep Southwestern Ontario, where we currently have a slight risk (2/5) for severe weather. The main hazard is damaging wind gusts between 12 and 6 AM, though isolated tornadoes and hail up to the size of quarters are also possible.

For the rest of Southwestern Ontario and the Golden Horseshoe, the risk is lower—a marginal (1/5) severe threat—with isolated pockets of wind damage being the most likely outcome. There’s also a very low tornado risk along the Lake Huron shoreline as the line initially pushes into the region. Hail up to the size of nickels could accompany some of these storms.

In addition to the overnight threat, a few isolated pop-up storms are possible during the late afternoon and early evening across parts of Grey-Bruce. While these are not expected to be severe, funnel clouds are possible, including a low-end risk of a landspout tornado. See our custom notification for more on the funnel cloud setup.

Stay weather-aware tonight. Keep your devices charged, notifications turned on, and have a plan in place just in case you need to take shelter quickly. We’ll continue to monitor the latest data and provide updates as the situation evolves, including a possible live stream later tonight.

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Understanding the Findings

Find out more & get notified

Ontario’s First Confirmed Tornado of 2025: EF0 Touches Down Near Woodstock Last Week

The Tornado: A Narrow but Confirmed Touchdown Near Lakeside

Timeline: Forecast Leading Up to the Tornado

Nocturnal Thunderstorm Threat With Damaging Wind Gusts and Isolated Tornado Risk for Southwestern Ontario Tonight

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