Ontario rolls into Labour Day enduring summer’s boldest heat
Ontario is in the midst of its hottest stretch of summertime heat as we round out the Labour Day weekend, and it’ll be a few days yet before relief is on the horizon.
Many communities across Ontario jutted past the 30-degree mark on Sunday, and we’re likely to see the heat build and repeat for several more days as a sturdy ridge of high pressure makes itself at home over the Great Lakes region.
A good portion of the region remains under heat warnings for the next several days, with the hottest conditions likely arriving by Tuesday and Wednesday. This level of spicy summer heat is quite unusual for the beginning of September.
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An unseasonably cool August failed to see any days with a high temperature of 30°C or warmer for much of the province. This was the first time in 15 years that Toronto failed to hit 30 degrees during the month of August.
Most folks across southern and eastern Ontario haven’t seen a daytime high of 30°C or warmer since July, with London, Kingston, and Cornwall making it nearly two full months without reaching the mark.
That streak is on borrowed time.
Sinking air beneath our growing ridge, combined with bright sunshine and humid winds blowing into the region, will lead to an extended spell of warm and muggy conditions across the entire province through the first half of the week.
We already saw the heat start to build over northern Ontario during the day Sunday.
Thunder Bay, Kapuskasing, and Moosonee all climbed above 30°C on Sunday afternoon. While Toronto-Pearson International Airport appears to have topped out just above 31°C, most areas in southern Ontario only climbed into the mid- to upper-20s on Sunday.
Sunday will seem like the cool old days for most as the ridge builds east and temperatures crank up throughout southern and eastern Ontario through the first half of the week.
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Daytime high temperatures will likely crack the 30-degree mark several days in a row for many communities. Forecasters expect most major cities, including Toronto and Ottawa, to see their longest stretch of 30+ degree highs of the summer through this week.
Toronto’s latest forecast calls for four days in a row of 30°C or warmer, besting the previous streak of three days hitting the mark.
Monday could rival the city’s warmest temperature of 2023, which currently stands at 32.3°C back on June 2. This is also likely to be the first time Toronto’s cracked 30 degrees during the month of September in three years.
The humid warmth will even push deep into cottage country and northern Ontario.
Several days of very warm temperatures are on the way for Barrie, Muskoka, and even farther north into Sudbury.
Thunder Bay will get in on the heat, as well, where Sunday’s predicted humidex of 43 could smash the month’s old record of 41 set back in 1998.
WATCH: Humidex records fall in northern Ontario as September heat broils the region
RELATED: The importance of staying hydrated in warm weather
While this week’s forecast is perfect for those who never want summer to end, the muggy conditions and bright sunshine carry dangers of their own.
It’s easy to overdo it in heat like this, especially with feels-like values creeping beyond 40 at times throughout Ontario. Even the fittest folks are susceptible to heat-related illnesses.
Drink plenty of water even before you feel thirsty and stay in a cool place.
Check on older family, friends and neighbours. Make sure they are cool and drinking water
Never leave people or pets inside a parked vehicle.
Outdoor workers should take regularly scheduled breaks in a cool place
The arrival of September marked the start of meteorological fall, though the autumnal equinox doesn’t officially occur until the wee morning hours of Saturday, Sept. 23.
Join us for the release of our 2023 Fall Forecast on Wednesday, Sept. 13. Our experts will take a look at temperature and precipitation trends for the upcoming season, revealing what you can expect during this highly changeable season across Canada.
WATCH: What longer, hotter, and more frequent heat waves means for your health
Stay tuned to The Weather Network for more forecast updates for Ontario.
