Widespread heat warnings are in effect for southern Quebec including metro Montreal, eastern Ontario, including Ottawa and the Champlain Valley of New York and Vermont. The combination of very warm temperatures and elevated humidity will make it feel closer to 40C today. Drink plenty of water and relax outdoor activities when possible. Dry to spend a portion of the day in air conditioned space. Montreal is already at 23C (73F) at 6am.
Monday will be the warmest day of the current heatwave, with high temperatures expected into the middle 30s across portions of southern Quebec, along with high humidity. We can expect a record-breaking high of 34C (94F) in Montreal, which should surpass the previous benchmark of 33.4C set in 1999. Gusty winds are also expected today from the southwest 30 to 50km/h, helping to pull in tropical air from the Gulf of Mexico.
On Sunday, the heat and humidity built up quickly after the afternoon thunderstorms on Saturday. The high was 31.4C (89F) in Montreal, also a record for the date beating the 2005 high of 30.8C (87F). The storms on Saturday became rather strong for portions of the city, with close to 15mm of rain falling in less than 30 minutes at Trudeau Airport. Locally, some parts of Montreal received over 30mm, but I only measured 4mm here on Ile Perrot, as the storms passed northeast of my location. Strong winds were observed as well, along with frequent lightning.
Monday should be dry for most of us, with just a slight risk of a shower or storm in the mountains well north and southeast of the St. Lawrence Valley. Showers and thunderstorms will increase on Tuesday ahead of a backdoor cold front. That front will cross the region early Wednesday, ushering in drier and slightly cooler air. Before then, expect a hot day Monday and Tuesday. The high on Tuesday will be near 31C, dropping to 30C for Wednesday. Overnight lows will be very warm, in the low to middle 20s in Montreal. Much cooler, more pleasant air arrives for Thursday, with a high of 24C (76F) forecast and lower humidity.
It is also important to note that a large portion of southern and western Quebec is under extreme fire conditions according to SOPFEU. Outdoor burning of any kind is not recommend, and in many regions is not permitted by law.
The ministère de la Santé et des Services sociaux du Québec, in co-operation with Environment and Climate Change Canada, recommends that you protect yourself from the effects of the heat by taking the following actions:
Drink 6 to 8 glasses of water per day. As appropriate, follow your physician's instructions regarding the amount of fluid to drink;
Avoid alcoholic beverages;
If you can, spend at least 2 hours a day in an air conditioned or cool place;
Take at least one cool shower or bath per day, or cool your skin several times per day with wet towels;
Limit physical activity;
Wear light clothes.
Never leave a child or a baby alone in a vehicle or a poorly ventilated room, even for a few minutes; Check on your loved ones, especially those who are vulnerable or living alone.