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Thursday morning storms prompt severe warnings in parts of southern Ontario

Thursday, July 29th 2021, 9:47 am - Early morning thunderstorms have prompted severe warnings for parts of southern Ontario.

Forget the alarm clock -- early morning storms across parts of southern Ontario were enough to wake some areas early Thursday. Severe thunderstorm warnings were issued before 7 a.m. in the southwest, with a cluster of storms near Sarnia continuing to move eastwards. Heavy downpours and strong wind gusts are the main threats, with widespread rain impacting much of southern Ontario through the better part of Thursday. Beyond the storms comes a noticeable cool down, where temperatures will remain well below seasonal for the August long weekend. More on the storm timing and impacts, plus a look at just how chilly things get, below.


A storm front that triggered severe thunderstorms in the far northwest on Wednesday has continued to push south, prompting early morning severe thunderstorm warnings across parts of southwestern Ontario.

"We're seeing an explosive cluster of storms drifting across the Midwest U.S., with frequent lightning and damaging winds likely as they cross over into southwestern Ontario this morning," says Jessie Uppal, a meteorologist at The Weather Network.

These thunderstorms are capable of producing very strong wind gusts between 90-100+ km/h, with locally heavy rainfall between 30-50 mm also expected.

"Heavy downpours are likely to cause flash floods and water pooling on roads," Environment Canada says in the warning.

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Elsewhere, the chances for widespread rain and rumbles of thunder will persist throughout Thursday, though with some clearing expected across the south later in the day.


A brisk northwest wind will knock temperatures even cooler for the start of the August long weekend on Friday, with daytime highs only reaching the lower 20s for southern areas, and remaining in the teens across cottage country and north of the St. Lawrence.

RELATED: August long weekend shows bold weather divide across Canada

Some sun will start the weekend on Saturday, but southern and central Ontario will quickly become cloudy with an increasing threat for rain late in the day. More widespread showers will push in for Saturday night and Sunday.


Gusty winds and a hint of autumn will be left behind the cold front on Sunday. Temperatures will likely remain in the teens across cottage country for the holiday on Monday, and for most of Quebec as well.

The comfortable, and cooler than seasonal pattern will continue into the start of next week, with a warming trend expected by the end of the week. Several computer models also highlight the potential for a more consistently warm and drier pattern as we head into the second week of August and beyond.

"Models have offered an abundance of false hope in the long range this summer, but we are closely watching to see if a warmer and drier pattern can finally get established," says Dr. Doug Gillham, another meteorologist at The Weather Network.

Stay with The Weather Network for the latest forecast across Ontario.

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