Heat and humidity return to Central Canada, elevating the thunderstorm risk in both Ontario and Quebec Thursday.
DON’T MISS: Dangerously hot weather about to spread back into Ontario again
Several lines of severe thunderstorms are expected to develop as humidity and instability peak during the afternoon and evening hours. Key factors driving this weather include moisture, instability, wind shear, and a low pressure system acting as a trigger.
While the main risks are hail, heavy downpours and potent, potentially damaging wind gusts, there is a chance of rotation and one or two tornadoes for parts of northeastern Ontario, Lake Huron-Georgian Bay shores and Quebec.
Baron – Ontario thunderstorm risk Thursday – July 24
Make sure you keep an eye on the radar––especially if you have outdoor plans––and stay aware of any severe weather watches or warnings issued in your area.
Thursday: Severe storm threat bubbles up with the rising humidity and instability
Southern and eastern Ontario will experience humidex values near 40°C during the afternoon, with dry conditions likely until storms develop in the evening hours.
Baron – Thursday temperatures Ontario – July 24
SEE ALSO: Dangerously hot weather spreads back into Ontario again
Timing: 4-5 p.m.
Thunderstorm activity is expected to begin as early as 4–5 p.m. in northeastern Ontario and parts of Quebec, where severe weather has the highest confidence.
Early-stage storm development may lead to isolated, rotating cells capable of producing tornadoes, particularly in Quebec.
Baron – Ontario precipitation Thursday 4 pm – July 24
Heavy rainfall is also a significant risk, with totals exceeding 50 mm locally due to multiple storm cells passing over the same areas. Localized flooding is a concern.
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7-8 p.m.
As storms mature, a transition to a more linear pattern is expected, increasing the likelihood of damaging wind gusts between 90–100+ km/h, particularly along Georgian Bay and Lake Huron Shores from 7–8 p.m. onwards.
Baron – Ontario precipitation Thursday 9 pm – July 24
Late evening and overnight:
Thunderstorms may reach the northern Greater Toronto Area (GTA) during the late evening or overnight hours, but will weaken as energy diminishes.
DON’T MISS: Why nocturnal thunderstorms can be particularly dangerous
Rainy periods could persist into Friday morning for parts of the GTA.
Baron – Ontario precipitation Friday 12 am – July 24
WATCH: In a tornado warning? Here’s what you should do
Signs of cooler weather for the August long weekend
Early next week, conditions will stay mostly sunny, hot, and humid, accompanied by a chance of passing thunderstorms. A strong cold front is expected to sweep south through the region midweek, bringing a heightened risk of thunderstorms.
By late next week, cooler air will settle in, with temperatures expected to remain below seasonal averages through the August long weekend and into the first week of the month. However, a return to significantly warmer weather is anticipated for the second week of August.
Stay with The Weather Network for more information and updates on your weather across Ontario and Quebec.
