Weathering the Storm: How to Prepare For an Ice Storm

In advance of the ice storm anticipated to impact the province, we at Instant Weather want to make sure that everyone is ready in the event of potential widespread and long term power outages. The impact of an ice storm is not just dependent on the amount of ice accretion, but also the winds associated with the storm. This is summarized using the Sperry-Piltz Ice Accumulation (SPIA) Index shown below.

It is important to be prepared for these situations so we have put together a list of items you should have on hand in case of an emergency:

• Flashlight (windup or battery operated)

• Radio (windup or battery operated)

• Extra batteries

• Portable cell phone charger

• Water (2 litres per person per day)

• Non-perishable canned or dried food

• Manual can opener

• Blankets

• Candles and matches or lighters

• First aid kit and any prescriptions/medical items

• List of emergency numbers

• Cash

• Gasoline

Not sure what kind of food to have ready? Dried food like rice and pasta along with canned tuna can go a long way. Other items such as bread and granola bars are good for fibre and non-refrigerated fruits like bananas, oranges and apples help break up the high-sodium content found in dried foods. Another staple for many are storm chips. For water, an easy way to store a large amount is to fill a bathtub and use the water for drinking, cooking, and flushing toilets.

Since ice storms occur during the winter and early spring months, keeping warm is a major concern during extended power outages from ice storms. Electric baseboard heaters and space heaters will not work. However, natural gas furnaces will still work, but electrical components such as the blower, which forces the warm air through the vents, will not. There are some propane heaters that can be used indoors, but be careful because outdoor propane heaters produce carbon monoxide, making them very dangerous to use inside a home.

Another item worth adding to your emergency kit arsenal is a generator. Generators are available in a variety of sizes and capacities based on individual needs. There are a few things to consider when picking a generator: type, power and additional features.

There are home standby generators that are permanently in place and start up automatically when the power goes out. These units are large and can be quite expensive. There are also smaller, portable generators that either run strictly on gas or on either gas or propane (dual fuel). There is an added benefit of running your generator on propane as it less expensive to run.

Every generator has two power ratings: starting watts and running watts. In order to determine the power of generator you need, you first need to determine what appliances will be running. In the event of an emergency, you may find that the only necessities are the fridge and furnace fan.

It is EXTREMELY important to not run a generator in your house due to the risk of carbon monoxide poisoning.

With proper planning and preparation, everyone should be able to get through the stress that comes with extended periods without power. In the case of an ice storm, it’s important to stay indoors and reduce unnecessary travel. Also, we recommend not clogging up emergency lines with non-emergencies. Your power will be back before you know it!

End-of-Year Major Winter Storm to Bring Dangerous Ice Storm and Blizzard Conditions Across Southern and Northeastern Ontario Starting Sunday

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As we close out 2025, the final few days are shaping up to be very messy and potentially dangerous. A complex and powerful winter storm is expected to impact Ontario between Sunday and Monday, bringing ice storm conditions to a wide swath of Central, Eastern and Northeastern Ontario.

With significant and prolonged freezing rain expected, widespread and long-lasting power outages are likely in the hardest hit areas. Ice accretion of up to 20mm is possible, and unfortunately, the regions most at risk include many of the same areas that were hit hard by last March’s major ice storm. In some locations, the power grid remains fragile, which raises additional concern.

Further north, the story will shift to heavy snow across much of Northeastern Ontario. Long-lasting blizzard conditions are possible here, with snowfall totals potentially exceeding 50cm by the time the storm finally winds down on Tuesday.

This system will also bring the risk of severe wind gusts across both Southern and Northern Ontario on Monday. Areas closest to the shorelines of the Great Lakes will be at the greatest risk, with damaging wind gusts in excess of 90 km/h possible. There may even be some isolated pockets, mainly in the Niagara region, that approach 100 km/h.

Southwestern Ontario will be largely unaffected by the first phase of the storm. Temperatures here will rise steadily on Sunday, peaking in the double digits by late afternoon or evening. Rain will fall steadily through Sunday and into early Monday. However, conditions will change rapidly as temperatures plunge Monday morning, creating a potential flash freeze as all that rainfall quickly freezes on roads and other surfaces.

Later on Monday, strong wind gusts will combine with steady, moderate snowfall around Lake Huron and Georgian Bay. Blizzard conditions could develop during the afternoon and evening as visibility drops and blowing snow becomes intense.

PRECIP TYPE - MAP FROM WEATHERBELL

The storm will begin to take shape late Sunday morning as the first bands of precipitation spread into Northeastern Ontario and parts of Southwestern Ontario. This will initially include some light freezing rain extending from London through Kitchener and Barrie.

TEMPERATURE - MAP FROM WEATHERBELL

Sunday afternoon will be heavily dependent on the position of the freezing line, which is expected to slowly expand northeastward. Areas to the southwest will gradually climb above freezing and escape the worst of the icing, while regions farther northeast remain locked below zero.

By around midday, most of Central and Eastern Ontario is expected to remain well below freezing. Higher elevation areas northwest of the GTA will hover close to the freezing mark, including Hamilton, Kitchener, Guelph and Orangeville. How long the cold air remains trapped at the surface will play a major role in how impactful the icing becomes in places like the Kitchener area.

Meanwhile, Deep Southwestern Ontario, including Windsor, will already be sitting in the mid single digits. Heavy rain will be ongoing here, but there will be no winter storm impacts during the day on Sunday.

PRECIP TYPE - MAP FROM WEATHERBELL

As Sunday afternoon progresses, the freezing rain shield will expand northward into the North Bay area and the Ottawa Valley. The heaviest icing during this time is expected to focus around Lake Simcoe.

Locations such as Bracebridge, Lindsay, Orillia, Peterborough, Barrie, York Region, Kitchener and Orangeville appear likely to see the worst icing on Sunday afternoon. Precipitation rates will be quite heavy, allowing ice to accumulate rapidly on roads, trees and power lines.

At the same time, Southwestern Ontario, including the Niagara region, will see heavy rain, with some embedded non-severe thunderstorms possible. Rainfall totals could be significant, with some localized areas exceeding 50mm by Monday morning.

At the same time, Southwestern Ontario, including the Niagara region, will see heavy rain, with some embedded non-severe thunderstorms possible. Rainfall totals could be significant, with some localized areas exceeding 50mm by Monday morning.

Flooding could be a concern as frozen ground has a lower ability to absorb the rain.

PRECIP TYPE - MAP FROM WEATHERBELL

As we move into Sunday evening, the freezing rain zone will become very expansive as the system rapidly intensifies. Intense icing is expected from Sault Ste. Marie through Sudbury and North Bay and into Central and Eastern Ontario.

Meanwhile, colder and more entrenched air across Northeastern Ontario will allow precipitation to switch over to heavy snow. Areas from Wawa to Kapuskasing will see snowfall rates increase significantly.

TEMPERATURE - MAP FROM WEATHERBELL

By late Sunday evening, uncertainty will increase across southern portions of Central and Eastern Ontario as temperatures hover very close to the freezing mark. This includes Barrie, Orillia, Muskoka, the Kawarthas, Peterborough and Kingston. If cold air proves even slightly more resilient than currently expected, these regions could remain below freezing overnight and continue to experience ice storm conditions.

In Deep Southwestern Ontario, it will feel almost surreal for late December, with temperatures climbing into the double digits even around midnight.

PRECIP TYPE - MAP FROM WEATHERBELL

Overnight Sunday into early Monday, heavy snowfall will expand farther south across Northeastern Ontario as colder air continues to advance. Areas including Sault Ste. Marie, Timmins and the Cochrane corridor are expected to transition from freezing rain to heavy snow.

This transition is especially concerning for the power grid, as heavy snow may accumulate on top of ice-coated trees and power lines. That combination could lead to significant damage, particularly in more remote and heavily forested areas.

For the Sudbury to Ottawa Valley corridor, freezing rain is expected to continue through the overnight hours with ice accumulation steadily increasing. This region is likely to see some of the worst overall impacts due to the length of time spent under freezing rain.

TEMPERATURE - MAP FROM WEATHERBELL

By late Monday morning, the next phase of the storm will unfold in the form of a flash freeze across Deep Southwestern Ontario. Rapidly falling temperatures will cause any remaining moisture to freeze quickly on untreated surfaces, creating extremely hazardous travel conditions.

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As freezing rain ends across Central and Eastern Ontario and temperatures drop by Monday afternoon, the true extent of the damage will become clear. Current data suggests the hardest hit areas may include Kawartha Lakes, Peterborough, Haliburton, Bancroft, Tweed, Kaladar, Renfrew, Perth and Ottawa. Ice accretion in these regions may range from 15 to 20mm, with localized pockets potentially approaching 25mm.

In the Ottawa Valley, temperatures may not rise above freezing at all before the flash freeze arrives. This would lock ice in place for an extended period, worsening impacts. Farther south, a brief window above freezing may help slightly reduce overall damage.

A broader area of Central and Eastern Ontario, along with higher elevations northwest of the GTA and parts of Northeastern Ontario, can expect between 10 and 15mm of ice. This includes Brockville, Kitchener, Guelph, Newmarket, Barrie, Muskoka, Parry Sound, North Bay, Sudbury and Sault Ste. Marie.

Ice amounts will decrease closer to Lake Ontario and away from higher terrain. Between 5 and 10mm is possible from Kingston through the northern GTA and higher elevations around Hamilton and Grimsby. Less than 5mm is expected for Oshawa, Mississauga, Hamilton and Meaford. Little to no icing is expected near Lake Huron and Lake Ontario, where temperatures remain above freezing for most of the event.

PRECIP TYPE - MAP FROM WEATHERBELL

While freezing rain will end, hazardous conditions will continue. By late Monday morning, rain will change to heavy snow around Lake Huron and Georgian Bay. Strengthening winds of 70 to 90 km/h will create dangerous travel conditions and likely meet blizzard criteria.

Combined with the flash freeze, widespread road closures are likely east of Lake Huron and into Northeastern Ontario. Travel should be avoided in these regions.

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The strongest wind gusts are expected during the morning and afternoon on Monday before slowly easing in the evening. Areas exposed to the lakes will see the worst winds, with gusts of 95 to 110 km/h possible across the Niagara region and into Prince Edward County.

Near damaging gusts of 85 to 95 km/h are possible along the Lake Ontario shoreline from Kingston through the GTA and Hamilton, as well as along the Lake Erie and Lake Huron shorelines and southeast of Georgian Bay into Simcoe County and Orangeville.

Elsewhere across Southwestern Ontario and southern portions of Central and Eastern Ontario, peak gusts of 75 to 85 km/h are expected. Farther north, including the Ottawa Valley, gusts will generally range from 65 to 75 km/h. While lower, these winds may cause greater damage due to occurring after significant ice accumulation.

Hourly snowfall rates (cm) - MAP FROM WEATHERBELL

Conditions will remain treacherous through Monday afternoon with strong winds and persistent snowfall, especially near the lakes, where blizzard conditions continue.

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Snowfall totals associated with the main system will wrap up by Tuesday morning. Central Ontario and parts of Southwestern Ontario east of Lake Huron can expect 5 to 15cm of snow, with localized totals exceeding 15cm near Kincardine, Hanover and Owen Sound due to lake enhancement.

Elsewhere across Southern Ontario, snowfall amounts will generally range from 2 to 5cm.

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In Northern Ontario, snowfall totals will be far more significant. The highest amounts are expected in Cochrane, Timmins, Chapleau and Kirkland Lake, where totals of 50 to 75cm are possible between Sunday evening and Tuesday morning.

A broader swath of Northeastern Ontario, including Wawa and Temiskaming Shores, may see 30 to 50cm. Areas such as Elliot Lake, Sault Ste. Marie and Kapuskasing could receive 20 to 30cm, while North Bay, Sudbury and Manitoulin Island are expected to pick up between 10 and 20cm.

Boxing Day Winter Storm Poised to Deliver Ice Storm Risk and Heavy Snow to Southern Ontario on Friday

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With Christmas now behind us, the focus turns to the final stretch of 2025 as we approach New Year’s next Thursday. And it’s looking like the last seven days of the year will be anything but quiet when it comes to the weather across Southern Ontario.

That active pattern becomes clear very quickly with a looming Boxing Day winter storm expected to bring a messy mix of precipitation. Some areas will see periods of heavy snowfall, while others could be dealing with a potentially damaging ice storm with prolonged freezing rain through much of the day.

For much of Central Ontario, along with parts of the Golden Horseshoe and into portions of Southeastern Ontario, the primary concern will be snowfall. Widespread totals in the 10 to 20 cm range are possible by the end of Friday. The Ottawa Valley is expected to remain on the lower end, generally staying under the 10 cm mark.

The forecast becomes more complicated through Southwestern Ontario, extending through Hamilton and into the Niagara Region. Here, a mix of snow and ice pellets is expected, which will limit snowfall totals but still create hazardous travel conditions.

The freezing rain risk has shifted slightly northward in the latest model guidance, as warmer air aloft is now expected to push deeper into Southern Ontario than earlier projections suggested. This places the Sarnia to London corridor in the bullseye for the highest ice accretion. Freezing rain totals of 10 to 15 mm are possible, which could result in significant power outages and very icy road conditions.

Beyond Friday, attention is already turning to another slow-moving system expected to arrive Sunday and linger into Monday. This system appears to have access to much more moisture compared to Friday’s storm, raising the concern for a prolonged period of freezing rain that could last anywhere from 12 to 24 hours.

What adds to the concern is that current model guidance is focusing this next threat over parts of Central and Eastern Ontario, the same areas that were hardest hit by last winter’s major ice storm. There is still uncertainty with the exact track, and it could shift north or south, but it is something we are watching very closely.

PRECIP TYPE - MAP FROM WEATHERBELL

Before we get ahead of ourselves, the immediate focus remains on Friday’s storm. Precipitation is expected to begin during the early to mid-morning hours as bands move in from the west. Light to moderate snow will spread into Grey-Bruce, Simcoe County, Muskoka and the GTA during this time.

For Windsor, Chatham and Sarnia, light freezing rain is expected to begin by mid-morning. Precipitation may be somewhat scattered at first but will steadily increase in coverage and intensity as the morning progresses.

PRECIP TYPE - MAP FROM WEATHERBELL

By late morning, the worst conditions should be underway, with heavy icing ongoing around Chatham, Sarnia and London. Travel conditions in these areas are expected to deteriorate quickly.

Further north and east, heavy snow will be the main concern across Muskoka, Simcoe County, Peterborough and the eastern GTA, including the City of Toronto.

Between the freezing rain to the southwest and the heavy snow to the north and east, a corridor of ice pellets is expected to develop from the Lake Huron shoreline through Kitchener and into Hamilton.

PRECIP TYPE - MAP FROM WEATHERBELL

Poor conditions will persist into Friday afternoon, with steady snowfall continuing across Central Ontario into Kingston. Wind gusts approaching 40 km/h may lead to localized blowing snow, further reducing visibility at times.

The ice pellet zone may also push further into the GTA, with Toronto potentially switching over to ice pellets for a time. This would limit snowfall totals and keep them closer to the 10 cm range.

Sarnia and London are expected to remain locked into freezing rain through much of the afternoon. There may be some hope for the Chatham area, where temperatures could briefly rise just above freezing and allow a changeover to rain by mid-afternoon. However, this is right on the line and could still go either way. Windsor and Leamington are expected to remain solidly in the rain zone.

PRECIP TYPE - MAP FROM WEATHERBELL

The system is expected to gradually wind down later Friday afternoon and into the early evening. Precipitation will taper off first across western areas, then slowly come to an end across the Golden Horseshoe and Eastern Ontario by late evening.

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Based on the latest data, the highest ice storm concern has been focused on the Sarnia, Lambton, Middlesex and London corridor. While there is still some disagreement on exact intensity, the potential exists for ice accretion exceeding 10 mm, with localized amounts approaching 15 mm.

Communities included in this higher risk zone include Wallaceburg, Sarnia, Petrolia, Thamesville, Lambton Shores, Grand Bend, St. Thomas and London.

Across Essex County, the highest ice accretion is expected in the northern portions of the county, including Windsor and Tilbury. These areas could see 5 to 10 mm of ice before a changeover to rain. Closer to the Lake Erie shoreline, including Leamington, icing should be minimal, generally under 2 mm, as temperatures rise above freezing more quickly.

Further north, freezing rain amounts will be reduced as ice pellets dominate initially, with freezing rain gradually mixing in later. Locations such as Lucan, Exeter, Woodstock, Tillsonburg, Simcoe, Port Colborne and Fort Erie could see a faster transition to freezing rain, with 5 to 10 mm of ice possible following a few hours of ice pellets.

For Huron and Perth counties, including Kitchener, Brantford and Niagara Falls, ice pellets are expected to linger longer. This will limit freezing rain to only a few hours near the end of the storm, with ice accretion generally in the 2 to 5 mm range. Less than 2 mm of icing is expected for Hamilton, Guelph and southern Grey-Bruce.

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On the snowfall side of the storm, the highest totals are expected to range from 10 to 20 cm across Northeastern Ontario, down into Central Ontario and parts of Eastern Ontario.

This includes areas such as Sudbury, North Bay, Parry Sound, Muskoka, Simcoe County, York Region, Toronto, Durham Region, the Kawarthas, Peterborough and Kingston.

Lower snowfall totals are expected in the Ottawa Valley, where amounts of 2 to 5 cm are forecast for Ottawa and 5 to 10 cm from Bancroft into Brockville. This is due to the core of the system’s moisture remaining further south.

South of the heaviest snow band, totals will decrease as ice pellets mix in later in the storm. Grey-Bruce, Orangeville, Guelph and the western GTA are currently expected to see 5 to 10 cm, though some model solutions suggest even less if mixing becomes more dominant.

Even lower snowfall totals are expected east of Lake Huron into Hamilton and Niagara, where less than 5 cm is forecast as ice pellets and freezing rain become the primary precipitation types.

PRECIP TYPE - MAP FROM WEATHERBELL

Once this system exits Friday night, Saturday should bring a brief period of calmer weather. However, that break will be short-lived, as another potentially high-impact winter storm is expected to approach as early as Sunday, possibly arriving in multiple waves.

The overall setup supports the potential for a prolonged area of freezing rain that could remain locked in place into Monday. This raises concern for a significant ice storm event, potentially similar in nature to last winter’s devastating storm across Central and Eastern Ontario.

Those same regions are once again in the early bullseye. While there is still time for this forecast to change, this is the type of setup where residents should begin thinking ahead and preparing for the possibility of extended power outages if the scenario does not improve.

We will continue to monitor this closely and will have a more detailed update once we get through Friday’s storm.

Potential Boxing Day Winter Storm Targets Southern Ontario With Significant Freezing Rain Risk and Up to 15-20cm of Snow

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While winter weather has mostly taken a breather across Southern Ontario over the past week, things are about to turn active again as we head into the final days of 2025.

That change begins on Boxing Day with a messy winter system expected to slide through Southern Ontario. This system will bring a wide range of hazards, including the threat of significant freezing rain in Deep Southwestern Ontario and more widespread snowfall across much of the rest of the region.

There are still some question marks surrounding this storm, particularly when it comes to how strong it ultimately becomes. Some lower-resolution models show a fairly robust system with plenty of moisture to work with. At the same time, higher resolution guidance that is now coming into range is hinting at some drier pockets, which could cause this system to underperform in spots.

Complicating matters further is the fact that this system has the characteristics of an Alberta Clipper. Clippers are notorious for being difficult to forecast since they often lack a deep source of moisture, and small changes can make a big difference in precipitation type and totals.

What we do know at this point is that impacts will vary significantly across Southern Ontario. The highest risk area continues to be Deep Southwestern Ontario, especially the Windsor, Chatham and Sarnia region, which currently sits in the bullseye for prolonged freezing rain.

In these areas, sustained freezing rain could lead to substantial ice accretion on roads, trees and power lines. This would result in dangerous travel conditions and an increased risk of power outages. With over 10mm of icing possible, there is also concern for widespread tree damage as branches struggle under the weight of the ice.

Further north, from areas east of Lake Huron through the Greater Toronto Area and into Central and Eastern Ontario, the primary precipitation type is expected to be snow. Snow will fall steadily through much of the day on Friday with general accumulations of 5 to 15cm by the end of the day. Locally higher amounts approaching 20cm are possible west of Lake Ontario around the Toronto area due to lake enhancement.

PRECIP TYPE - MAP FROM WEATHERBELL

The first bands of precipitation are expected to arrive early to mid-morning on Friday, spreading across Lake Huron into Southwestern Ontario. As the system moves in, it will encounter a stubborn layer of cold air near the surface across Deep Southwestern Ontario, including Windsor, Leamington, Chatham and Sarnia.

At the same time, warmer air will surge in above the surface, creating a classic setup for freezing rain. This warm layer aloft melts the snow into rain, which then freezes on contact with cold surfaces at the ground.

850MB TEMPS (1.5KM ABOVE GROUND) - MAP FROM WEATHERBELL

The biggest challenge with events like this is determining how far north and how deep that warm layer extends. This is the key factor that decides whether precipitation falls as ice pellets or as freezing rain.

Temperatures roughly 1.5km above the surface vary considerably between models. The Canadian model is more aggressive, pushing the warm layer farther north into Southwestern Ontario and even as far as London.

Overall, model consensus places the freezing line somewhere near a Sarnia to London corridor. Areas south of this line are more likely to see freezing rain, while areas to the north will see a mix of ice pellets and snow.

PRECIP TYPE - MAP FROM WEATHERBELL

By the early afternoon, heavier snow will begin spreading into Central Ontario and the Golden Horseshoe as precipitation from Northern Ontario moves southeast across Georgian Bay. At the same time, freezing rain will be ongoing around Windsor, Chatham and Sarnia.

There are indications that temperatures may slowly climb above freezing for southern Essex County, including Leamington and eventually Windsor. There is still disagreement on the exact timing of this changeover, but it appears most likely sometime during the early to mid-afternoon.

If temperatures do rise above freezing, freezing rain would switch to plain rain, and any ice accretion would begin to melt. How quickly this happens will be critical in determining overall impacts. If the warmup is delayed until later in the day or temperatures stubbornly remain below freezing before dropping Friday night again, impacts could be significantly worse.

For areas like Chatham-Kent, Sarnia and St. Thomas, there is growing concern that temperatures may remain below freezing for much of the event. This would allow ice to accumulate for a prolonged period, with over 10mm of accretion possible. Ice amounts of this magnitude are capable of bringing down tree limbs and power lines, potentially leading to power outages that could last for several days.

Hourly snowfall rates (cm) - MAP FROM WEATHERBELL

By mid-afternoon, the heaviest snow will be pushing through the Golden Horseshoe. Some models are showing the potential for lake enhancement along the Lake Ontario shoreline from Niagara through Hamilton and into Toronto. If this develops, snowfall rates could briefly spike to 3 to 5cm per hour compared to the more general 1 to 2cm per hour elsewhere.

It is also important to note that ice pellets may mix in at times, which can limit snowfall totals since ice pellets are denser than snow. This is most likely for areas such as London, Kitchener, Hamilton and Niagara, where conditions are more supportive of mixed precipitation. Areas closer to Toronto and farther north into Central Ontario should see more consistent snow.

Light to moderate snow will also spread into Eastern Ontario by the afternoon and continue into the evening before tapering off around midnight. Confidence in snowfall totals here is lower, but amounts in the 5 to 10cm range appear possible by the end of the day.

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While there is decent agreement on the overall track of this system, fluctuations are still very likely. Freezing rain events are among the most difficult to forecast, and even small temperature changes can have major impacts.

At this time, the highest confidence for the worst impacts remains across the Chatham, Windsor and St. Thomas area, where a persistent band of freezing rain is expected to set up for much of the day on Friday. Some models show up to 20mm of liquid precipitation, though not all of that would freeze on surfaces. For now, we are forecasting over 10mm of ice accretion, with the understanding that an overachieving scenario is still on the table.

For southern Essex County, including Leamington and possibly southern Windsor, ice accretion of 5 to 10mm is possible before a changeover to rain. Because of this transition, overall impacts should be lower compared to areas farther north, where freezing rain may last longer.

Farther north, from Sarnia through London and into Norfolk County, precipitation may begin as ice pellets in the morning before transitioning to freezing rain later in the afternoon or early evening. Ice accretion here could range from 3 to 8mm, depending on how quickly this transition occurs.

A corridor stretching from Goderich through Kitchener, Hamilton and into the Niagara region is expected to start with heavier snow Friday afternoon. Mixing with ice pellets later in the day could reduce snowfall totals, with most areas seeing around 5 to 10cm by the end of the event.

Areas that remain predominantly snow from start to finish include Grey-Bruce, much of Central Ontario, Eastern Ontario and the eastern portions of the GTA. Snowfall totals here should generally range from 10 to 15cm, with localized amounts up to 20cm. In Eastern Ontario, especially closer to the Quebec border, totals may struggle to reach 10cm, making 5 to 10cm a more realistic expectation.

We will continue to monitor the latest data closely and will have a more detailed and refined forecast on Thursday night. That update will provide a clearer breakdown of precipitation types and expected amounts. Be sure to check back for the final forecast.

Dangerous Ice Storm Likely This Weekend With Widespread Power Outages Across Parts of Southern Ontario

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Concern is rapidly growing for what is shaping up to be a potentially devastating ice storm this weekend across parts of Central and Eastern Ontario. Prolonged freezing rain, beginning Friday evening, is expected to persist throughout much of the weekend, leading to substantial ice accretion on exposed surfaces.

This storm has the potential to reach ice accumulation levels not seen in years—or even over a decade. With up to 40mm of ice accretion possible, widespread power outages are likely in the hardest-hit regions, including Muskoka, Simcoe County, Kawartha Lakes, Peterborough, and Kingston.

Some of these power outages could last for days or even weeks, especially in more rural areas with dense tree coverage. Trees weighed down by ice are likely to fall, taking power lines with them. Travel conditions will also be significantly impacted, as ice-covered roads become extremely dangerous.

For Northern Ontario, the storm will start as a classic winter system, bringing heavy snowfall to Northeastern Ontario throughout Saturday. A second round of precipitation on Sunday could introduce freezing rain and ice pellets further south, affecting areas like Elliot Lake, Sudbury, and North Bay. Snowfall totals in Northeastern Ontario are expected to range from 20 to 30cm, making travel difficult.

Even the Ottawa Valley will see significant snowfall, with up to 20cm possible, along with a mix of ice pellets. By Sunday, freezing rain could become a concern for the region as temperatures rise and the precipitation type shifts.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

As of Friday afternoon, rain is already moving into Southwestern Ontario. By the evening, precipitation will spread north and east into Central and Eastern Ontario.

Based on the latest data, a band of heavy snow is expected to develop along a corridor stretching from Sudbury through North Bay and into the Ottawa region. To the south, an area of freezing rain will form over the Bruce Peninsula and extend into regions around Lake Simcoe.

ESTIMATED TEMPERATURE - MAP FROM WEATHERBELL

How far south the freezing rain spreads remains uncertain. Model guidance suggests surface temperatures will hover near the freezing mark across Barrie and the Greater Toronto Area (GTA).

Even a fraction of a degree difference could significantly alter how much freezing rain accumulates. If the air remains colder than expected, freezing rain could be more widespread. However, a slightly warmer scenario would push the freezing rain line further north.

Confidence is highest for freezing rain in northern sections of Simcoe County, Kawartha Lakes, and Muskoka. These areas are most likely to remain below freezing for an extended period, allowing heavy ice accretion to build up.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

The most intense icing is expected overnight into early Saturday morning. The worst conditions will stretch from Muskoka through Peterborough and into Kingston.

Once again, temperature will be the deciding factor. Some areas, such as Barrie and Newmarket, sit right on the edge between freezing rain and regular rain. If cold air lingers longer than anticipated, freezing rain could extend as far south as the northern GTA, as well as higher elevations like the Dundalk Highlands.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Through Saturday morning and afternoon, light to moderate freezing rain or drizzle is expected to persist across portions of Central Ontario, particularly around Lake Simcoe. However, the intensity will decrease compared to the earlier hours.

Further south, rain will continue across Southwestern Ontario and the GTA. This is when we expect the warmest temperatures of the storm. Some areas in Deep Southwestern Ontario, including Windsor, could surge into the 20s, while Central Ontario remains near or below freezing.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

By Saturday evening, another round of heavy precipitation is expected to push into Central Ontario. At the same time, temperatures will steadily drop. Regions that saw rain in the afternoon—including parts of the GTA and Barrie—may transition back to freezing rain.

ESTIMATED TEMPERATURE - MAP FROM WEATHERBELL

Model data suggests that by late Saturday night into Sunday morning, the freezing rain line could shift southwest of the GTA. This could result in several hours of freezing rain across Kitchener, Waterloo, and parts of the Toronto area.

Deep Southwestern Ontario, including Windsor, Sarnia, and London, is expected to remain unaffected, staying well above freezing.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Sunday morning will bring a gradual transition from freezing rain to regular rain across the GTA as temperatures climb above freezing. However, elevated areas northwest of the city, such as Guelph, Orangeville, and Shelburne, could see freezing rain linger for a few extra hours.

For Central Ontario, the freezing rain will continue into early Sunday afternoon as the main area of precipitation slowly shifts north.

By Sunday afternoon, the Ottawa Valley may begin transitioning from snow to ice pellets and then to freezing rain as temperatures rise.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Most of Southern Ontario will warm above the freezing mark by late Sunday, finally pushing the freezing rain threat northward.

However, by Sunday night into Monday morning, the risk of freezing rain will shift to Northeastern Ontario, including Sudbury and North Bay.

Meanwhile, heavy snow and ice pellets will impact more northern regions, such as Wawa and Timmins.

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Predicting exact ice accretion remains challenging, as many factors influence how much ice actually builds up. The amount of freezing rain you experience may vary significantly from nearby areas due to microclimate effects, surface conditions, and temperature fluctuations.

Some high-resolution model runs suggest an extreme scenario with localized pockets of over 50mm—possibly even 75mm—of freezing rain. However, because much of this precipitation will fall in a relatively short timeframe, not all of it will necessarily adhere to surfaces.

Given this, we are forecasting general ice accretion between 25 and 40mm in the hardest-hit areas. This includes the northern tip of the Bruce Peninsula, Muskoka, Orillia, Barrie, Orangeville, Collingwood, Lindsay, Peterborough, Belleville, and Kingston.

If temperatures are slightly colder than expected, some locations could exceed 40mm of ice accretion, particularly where conditions allow for more efficient accumulation.

To put this into perspective, we can use the Sperry-Piltz Ice Accumulation Index (SPIA Index). With forecasted ice accumulations of 25-40mm (1-1.4”), this storm falls into a Category 4 ice event—even before factoring in wind.

While we are not expecting extreme winds, gusts of 40-50km/h (25-30 mph) in some areas could push this storm into Category 5 territory. According to the SPIA Index, a Category 5 ice storm results in:

Catastrophic damage to entire exposed utility systems, including both distribution and transmission networks. Outages could last several weeks in some areas. Shelters needed.

For the Greater Toronto Area (GTA), ice accretion amounts will vary significantly. The biggest factor will be how long cold air remains trapped at the surface.

We currently expect between 10-15mm of ice for northern parts of the GTA, including York, Durham, and Peel regions. Kitchener and Waterloo will likely see between 5-10mm.

Closer to the Lake Ontario shoreline—including downtown Toronto—freezing rain amounts should be lower, around 2-5mm. However, if temperatures are colder than expected, ice accretion in the GTA could be higher, so it’s still best to prepare.

To the north, ice accretion amounts will drop off as freezing rain transitions to ice pellets and snow closer to the Ottawa Valley.

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In terms of snowfall, widespread totals between 20-30cm are expected across much of Northeastern Ontario through Monday. This includes Sudbury, North Bay, Chapleau, Timmins, and Kirkland Lake. Even Thunder Bay could see 10-20cm of snow, mainly earlier in the weekend.

Along the Quebec border, snowfall amounts will range from 10-20cm in areas like the Ottawa Valley and Cornwall. Further southwest, freezing rain and ice pellets will be the dominant concern, leading to lower snowfall totals.

This storm remains highly dynamic, with small temperature fluctuations potentially making a massive difference in what type of precipitation falls. We will continue to monitor the latest data and provide updates as the situation evolves. Stay safe and stay prepared.

Weathering the Storm: How to Prepare For an Ice Storm

In advance of the ice storm anticipated to impact the province, we at Instant Weather want to make sure that everyone is ready in the event of potential widespread and long term power outages. The impact of an ice storm is not just dependent on the amount of ice accretion, but also the winds associated with the storm. This is summarized using the Sperry-Piltz Ice Accumulation (SPIA) Index shown below.

It is important to be prepared for these situations so we have put together a list of items you should have on hand in case of an emergency:

• Flashlight (windup or battery operated)

• Radio (windup or battery operated)

• Extra batteries

• Portable cell phone charger

• Water (2 litres per person per day)

• Non-perishable canned or dried food

• Manual can opener

• Blankets

• Candles and matches or lighters

• First aid kit and any prescriptions/medical items

• List of emergency numbers

• Cash

• Gasoline

Not sure what kind of food to have ready? Dried food like rice and pasta along with canned tuna can go a long way. Other items such as bread and granola bars are good for fibre and non-refrigerated fruits like bananas, oranges and apples help break up the high-sodium content found in dried foods. Another staple for many are storm chips. For water, an easy way to store a large amount is to fill a bathtub and use the water for drinking, cooking, and flushing toilets.

Since ice storms occur during the winter and early spring months, keeping warm is a major concern during extended power outages from ice storms. Electric baseboard heaters and space heaters will not work. However, natural gas furnaces will still work, but electrical components such as the blower, which forces the warm air through the vents, will not. There are some propane heaters that can be used indoors, but be careful because outdoor propane heaters produce carbon monoxide, making them very dangerous to use inside a home.

Another item worth adding to your emergency kit arsenal is a generator. Generators are available in a variety of sizes and capacities based on individual needs. There are a few things to consider when picking a generator: type, power and additional features.

There are home standby generators that are permanently in place and start up automatically when the power goes out. These units are large and can be quite expensive. There are also smaller, portable generators that either run strictly on gas or on either gas or propane (dual fuel). There is an added benefit of running your generator on propane as it less expensive to run.

Every generator has two power ratings: starting watts and running watts. In order to determine the power of generator you need, you first need to determine what appliances will be running. In the event of an emergency, you may find that the only necessities are the fridge and furnace fan.

It is EXTREMELY important to not run a generator in your house due to the risk of carbon monoxide poisoning.

With proper planning and preparation, everyone should be able to get through the stress that comes with extended periods without power. In the case of an ice storm, it’s important to stay indoors and reduce unnecessary travel. Also, we recommend not clogging up emergency lines with non-emergencies. Your power will be back before you know it!

Potential Major Ice Storm Threat on the Horizon for Southern Ontario This Weekend

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With the end of March approaching and the arrival of April, winter’s grip on Southern Ontario is loosening. However, Old Man Winter isn’t leaving quietly. Instead, the final days of March bring the potential for multiple rounds of heavy freezing rain across parts of the region.

The risk of freezing rain is set to begin late Friday as the first wave of precipitation moves in. This initial bout of freezing rain could be quite heavy at times, particularly across Central and Southern portions of Eastern Ontario. The Greater Toronto Area (GTA) may also see some freezing rain late Friday before transitioning to regular rain as temperatures rise overnight.

A second wave of freezing rain is expected to develop Saturday evening and continue through Sunday. However, this round carries more uncertainty, with forecast models disagreeing on how far north warm air will push at the surface. Some models concentrate the freezing rain in Northeastern Ontario and the Ottawa Valley, while others bring it much farther south, placing the GTA in the bullseye.

While there is still uncertainty regarding the exact track and intensity of the freezing rain, all major weather models agree on the overall setup. Cold air will remain locked in at the surface across parts of Southern Ontario, while a surge of warm air moves in aloft. This combination will create ideal conditions for freezing rain formation.

These conditions are expected to persist throughout much of the weekend, with multiple waves of freezing rain possible. Given the prolonged duration of freezing rain, significant impacts are likely. Thick layers of ice could accumulate on untreated surfaces, including trees and power lines. The weight of this ice may lead to substantial damage to the power grid, with outages that could take days—or even weeks—to repair.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Focusing on the first round, models are beginning to develop a clearer picture of where freezing rain will be most intense. Initial bands of precipitation should move into Southwestern Ontario by late Friday afternoon or evening.

As this precipitation reaches areas such as Kitchener, Owen Sound, and Barrie, it will encounter stubborn below-freezing temperatures at the surface. This will lead to freezing rain developing across these regions.

Further north, a band of heavy snow is expected to spread across areas near the northern shoreline of Lake Superior, extending into Timmins. In more southern locations, such as Sault Ste. Marie, Sudbury, and North Bay, ice pellets will likely be the dominant form of precipitation.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Models agree that warm air associated with this system will gradually work its way toward the surface, beginning in the southwest and pushing northeast through the night. As a result, some freezing rain may mix with regular rain, especially southwest of Lake Simcoe and near the Lake Ontario shoreline in the GTA.

The persistence of cold air at the surface remains a major question mark. Some models suggest that cold air will be more stubborn, leading to more sustained freezing rain in the GTA overnight and into Saturday morning.

What is more certain is that a particularly intense band of freezing rain will set up over Central Ontario, including the Bruce Peninsula, Muskoka, Simcoe County, Peterborough, and Kingston. Significant ice accumulation is expected in these areas, with freezing rain continuing into Saturday morning. While freezing rain will persist into the afternoon, it should gradually become more scattered in nature.

In the Ottawa Valley, ice pellets and snow will be the main concern. There remains uncertainty regarding snowfall totals, as accumulation will depend on how much mixing occurs with ice pellets. Estimates currently range from 10 to 20 cm, but if ice pellets dominate, snowfall amounts could be closer to 5 cm.

TEMPERATURE - MAP FROM WEATHERBELL

Looking at the temperature setup for this event, a sharp gradient will be present across Southern Ontario on Saturday morning. This is one of the factors making this forecast so tricky.

Below-freezing temperatures will be well-established over Central and Eastern Ontario, as indicated by areas northeast of the pink line on the map above. Meanwhile, Deep Southwestern Ontario—including Windsor, Sarnia, and London—will experience double-digit temperatures, with no threat of wintry precipitation.

The most uncertain area lies between the orange and pink lines on the map above. This includes much of the GTA and the Grey-Bruce region. Temperatures in these areas will hover near the freezing mark, placing them at the boundary between warm and cold air. If models are off by just a degree or two, it could mean the difference between an ice storm and plain rain.

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This represents our preliminary assessment of the hardest-hit areas from the first round of freezing rain. It’s important to note that this forecast covers conditions through Saturday night, but the threat of freezing rain will persist into Sunday and even Monday. There is less certainty regarding how the second round will play out, so our focus remains on the first round for now.

Confidence is highest for significant ice storm impacts in locations such as Tobermory, Wiarton, Owen Sound, Collingwood, Orangeville, Barrie, Midland, Orillia, Muskoka, Parry Sound, Peterborough, and Kingston. Ice accretion in these areas will likely exceed 10 mm and could even reach 20 to 30 mm in the worst-case scenarios.

As previously discussed, temperatures will play a crucial role in determining the extent of freezing rain along the narrow corridor that includes the GTA and Kitchener. Slightly colder temperatures could mean prolonged freezing rain, while a warmer solution would allow for a quicker transition to rain overnight Friday.

Those in Deep Southwestern Ontario and along the Lake Erie shoreline should see little impact, as temperatures will remain well above freezing, resulting in plain rain rather than freezing precipitation.

For more northern regions along the Quebec border, ice pellets and snow will be the dominant precipitation types. Locations such as North Bay, Pembroke, and Ottawa could see 10+ cm of snow, with a risk of ice pellets and possibly brief periods of freezing rain.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

As the first round of freezing rain winds down across Southern Ontario, lingering pockets of freezing drizzle may persist across Central and Eastern Ontario through Saturday afternoon. In the GTA, temperatures could dip just enough to allow for a transition back to freezing rain later in the day.

The second round of freezing rain is expected to arrive by Saturday evening as energy moves in from the U.S. Midwest.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

Models are in solid agreement that this second wave will set up another band of freezing rain in the same areas hit hardest by the first round, including Central Ontario and portions of the GTA. This freezing rain will persist overnight into Sunday morning. However, by Sunday morning, the models begin to diverge significantly.

A more northern track would see warm air winning out across Southern Ontario, allowing temperatures to rise and leading to a transition to rain near Lake Simcoe. This would push the freezing line northward into Northeastern Ontario and the Ottawa Valley. In this scenario, freezing rain would be confined to areas such as Sudbury and North Bay, while heavy snow would develop from Wawa to Timmins.

Both the Canadian and European models favor this northern solution, which would be the better outcome for Southern Ontario, as it would avoid a second major icing event. However, this would be worse news for Sudbury and North Bay, where a significant ice storm could unfold.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

This more northern track has the warmer air winning out across Southern Ontario during the morning on Sunday. This gradually leads to a switch over to rain near Lake Simcoe as the freezing line puches north into Northeastern Ontario and the Ottawa Valley.

Then freezing rain would be contained to Northeastern Ontario including Sudbury and North Bay. While heavy snow extends from Wawa to Timmins.

Both the Canadian and European models favor this solution. Which would certainly be the better outcome for Southern Ontario as they escape a second icing event. But would be worst news for Sudbury and North Bay which could see an ice storm.

PRECIPITATION TYPE - MAP FROM WEATHERBELL

On the other hand, the American model suggests a much more southerly track, which would place Southwestern Ontario and the Golden Horseshoe directly in the path of heavy icing. This scenario would bring freezing rain through Sunday night into Monday morning, creating hazardous conditions for the Monday morning commute.

If this outcome materializes, widespread school bus cancellations across Southern Ontario would be likely on Monday morning. Meanwhile, areas farther north could see accumulating snow on top of earlier ice buildup.

Unfortunately, a significant cooldown is expected in the wake of this storm. By Monday evening, temperatures will plunge into the negative teens. Any ice that accumulates over the weekend will remain in place for several days, increasing the strain on the power grid as trees continue to fall onto power lines.

Regardless of how this storm unfolds, it is shaping up to be a high-impact winter event with potentially severe consequences in some areas. Prepare for treacherous travel conditions and the possibility of widespread power outages lasting multiple days.

We will provide further updates as the weekend approaches. Stay tuned and stay safe!