Hail, strong winds, heavy rain: Ontario's thunderstorm chances rise

While Ontario gets a taste of summer for the long weekend, that includes pleasant and potentially stormy weather. The risk of thunderstorms in Ontario will shift as we progress over the next couple of days, so be sure to stay alert and follow the forecast

While some areas of the country are dealing with snow this long weekend, Ontario is getting treated to more reflective weather to what many look to as the unofficial kickoff to summer.

While that means heat and humidity for Ontario, and sunshine at times, it also brings the threat of thunderstorms Sunday, Monday and into the start of the new work week for many. Come Tuesday, however, some of the recent, wintry weather on the Prairies moves into northwestern Ontario.

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Stay close to safe shelter if you have outdoor plans this weekend and on Tuesday. If you can hear thunder, you’re close enough to get struck by lightning.

Sunday, Monday storm threats for parts of northern, central and southern Ontario

Storm threats are building by the day across Ontario, along with the heat.

Ontario storm risk map through Sunday night

Sunday evening will storms fire ahead of the warm front, so many folks could be treated to a light show through the late-evening and overnight periods.

Storms will be generally non-severe, but hazards include heavy downpours, small hail and gusty winds.

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These clusters of storms will be more organized over cottage country and northeastern Ontario as the frontal system lifts north, but the Greater Toronto Area (GTA) could still see a storm after midnight.

Ontario precipitation timing early Monday morning

On Monday, southern Ontario will be comfortably in the warm sector--by far the warmest day of the year for the region.

This will likely be the first 30-degree day at Toronto’s Pearson International Airport.

On Monday night, a cold front attempts to slice across southern Ontario, but fails to make much headway.

Ontario precipitation timing Monday evening

Thunderstorms are still possible along the Lake Huron shores and cottage country on Monday evening, where storms will be better organized and may approach severe limits.

Storm mode linear: Strong, potentially damaging winds and large hail are primary threats

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Ontario storm risk map Monday

Tuesday storm threat builds in southern Ontario

Southern Ontario once again finds itself in the warm sector of another developing Colorado low, with the centre tracking towards Lake Superior through the afternoon before slicing into western Quebec by early Wednesday morning.

Thunderstorms are expected across southern Ontario later Tuesday evening and overnight, being triggered by the approaching cold front.

Ontario precipitation timing Tuesday afternoon

Marginal severe threat exists, but the confidence is low.

By Wednesday, temperatures have fallen sharply across most of southern Ontario, with a wedge of warmer air ahead of the cold front holding on across extreme eastern Ontario.

Wintry weather moves into northern Ontario

To the north, a much different story is at play.

No, not a joke, but regions across northwestern Ontario on Tuesday will be subject to a wintry mix. We’re paying close attention to the weather near and north of Thunder Bay, where the risk of ice pellets, freezing rain, and even wet snow exists along and north of the Lake Superior shores.

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Ontario precipitation timing Tuesday morning

Communities likely impacted include:

  • Dryden

  • Armstrong

  • Moosonee

  • Geraldton

  • Nipigon

  • Fort Hope

  • Atikokan

  • Marathon

The freezing line near Thunder Bay will have to be monitored closely for the threat of a developing, wintry mix on Tuesday.

Thunderstorm safety is vital on a holiday weekend

A warm holiday weekend guarantees that plenty of folks will spend time outdoors in the days ahead, making thunderstorm safety paramount.

Lightning can strike dozens of kilometres away from the heart of a storm. If you’re close enough to hear thunder, you’re close enough to get struck by lightning. If someone nearby is struck by lightning, don’t wait to render aid! It’s a myth that it’s dangerous to touch a lightning strike victim.

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Severe weather can strike suddenly. Flying debris and falling trees are a significant hazard during a storm’s sudden high winds. Large hail is dangerous to anyone caught outdoors.

Make sure you have a way to receive severe weather warnings the moment they’re issued.

Header image created using graphics and imagery from Canva.

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