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Southern Québec is bracing for a major shift in the weather, with heavy rain, possible thunderstorms and chilly temperatures in the forecast.
While summer-like heat returns to parts of Ontario, Montréal and surrounding regions could see up to 60 mm of rain by Wednesday.
Read: Canada’s fall forecast 2026 by region
According to a report by MétéoMédia, here’s what to expect across Québec.
When will the rain arrive in Montreal?
A powerful weather system moving toward Québec is expected to bring significant rainfall starting Tuesday morning. A special weather statement is in effect for several areas of southern Québec, including Montréal, Montérégie, the Eastern Townships and Beauce.
Between 40 and 60 mm of rain could fall in some areas by Wednesday, with the heaviest precipitation potentially arriving Tuesday afternoon and evening.
Check out: Best indoor things to do in Montreal when it rains
A warm front is set bring an initial band of precipitation on Tuesday morning, which could be particularly intense across southern Ontario. The transition toward Montréal is expected in the morning, with the remnants of this heavy rainfall arriving in the afternoon and potentially continuing into the evening.
The system is part of a broader weather pattern creating a sharp contrast between Québec and Ontario. While southern Ontario prepares for summer-like temperatures, Québec is caught between two air masses, bringing more variable conditions.
As Ontario enjoys a brief return to summer, Québec is set to remain much cooler. On Tuesday afternoon, temperatures in Windsor could climb to 28°C, with a humidex near 35. Montréal, by contrast, is forecast to reach just 10°C.
The temperature difference highlights the contrasting weather conditions on either side of the Québec–Ontario border, as a warm air mass settles over southern Ontario while cooler, more changeable conditions persist in Québec.
Could thunderstorms hit Québec on Tuesday?
Along with heavy rain, the incoming system brings a risk of thunderstorms. Some of these thunderstorms could extend into Tuesday, however, heavy rainfall is expected to be the main weather concern for the province.
October has already been unusually active for thunderstorms in Québec. The province typically records an average of five thunderstorm days during the month, but as of October 12, it has already experienced seven.
The month got off to a stormy start, with lightning and thunder waking residents across the greater Montréal area on October 7.
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