Strong thunderstorms possible Thursday - cooler weather returns Friday

Strong thunderstorms, some with heavy rain are possible again on Thursday, but at this time we are not expecting a repeat of the widespread flash flooding that occurred this past Sunday. (Photo: Domenic Fazioli)

6AM: Severe Thunderstorm Watch posted for metro Montreal.

Heat Warning remain in effect. Expect thunderstorms today, with strong winds and heavy rainfall possible.

The heat warning remains in effect for one more day across southern Quebec, but cloud cover and thunderstorms should keep our high temperatures under 30C Thursday. Trudeau Airport reached 32.6C (91F) on Wednesday, with a record overnight low of only 25.4C (77F). 

The end of the current heatwave is in sight, as a strong cold front is forecast to sweep across eastern Ontario and southern Quebec Thursday. In advance of that front, temperatures will warm to 29C (85F) in Montreal today. Some isolated storms are occurring this morning, but stronger, more widespread activity is likely this afternoon.

ECCC thunderstorm outlook for Thursday. Strong thunderstorms are possible in Montreal and across southern and eastern Quebec, with gusty winds the main threat.

At this time, we are not looking at a repeat of Sunday's flash flooding that occurred across the city, but some of the storms could be severe, with strong winds being the main threat. A few cells may have heavy rain, but they are expected to be moving faster than the weekend activity, therefore lowering the flood risk for Montreal. That being said, there could still be some localized water accumulation, so listen for any weather watches or warnings that may be issued later today.

A few storms may be strong enough to produce an isolated tornado or two. The main risk area would be in eastern Ontario from Ottawa towards Cornwall, Upstate New York and Vermont, as well as the Eastern Townships and Beauce regions closest to the American border.

Outside of the thunderstorms, expect another warm and humid day, with gusty southwest winds in the 30-50km/h range. Those winds will back to the north tonight.

Overnight, a refreshing air mass will arrive, with lowering temperature and humidity levels. By morning, lows may be in the lower teens. Friday will be a spectacular summer day, with sunshine, low humidity and a high of 24C (76F). Saturday will be sunny and pleasant as well, before showers return for Sunday.