TORONTO — Dangerously high temperatures persisted on Monday across much of Ontario and southwestern Quebec, as residents tried to keep cool under a lingering heat dome.
Environment Canada said the heat wave that began on Sunday will likely continue until Wednesday, with daytime highs of up to 36 C and humidex values between 42 and 46 C.
New heat records may be set across the province on Monday, said Environment Canada meteorologist Geoff Coulson.
Toronto appeared to break the heat record for June 23 that was set in 1983 when the temperature recorded by Environment Canada at Pearson airport reached 36 C late Monday afternoon.
Cities including Windsor, Kitchener-Waterloo and Ottawa were also at risk of breaking temperature records, Coulson said, noting that 18 other locations in Ontario set new heat records on Sunday.
Following a relatively cool spring, Coulson said this heat dome is "almost a worse scenario" since people are not yet acclimatized to high heat and humidex readings "well above normal for this time of year."
Amid the sweltering conditions, thousands of people in parts of central and eastern Ontario are without power after severe weekend thunderstorms.
Hydro One says its power restoration crews are "out in full force" and expect to make significant progress on Monday but warned that some of the affected customers may be without electricity until Tuesday.
"Given the extreme heat forecasted for the next few days, customers are encouraged to visit their municipality or township’s website for information on cooling centres," Hydro One said on its website.
In Toronto, more than 500 cooling spaces have opened and the city said some outdoor pools will stay open until nearly midnight on Monday. However, the city temporarily closed some pools on Sunday, citing the need to ensure "staff health and safety" when temperatures reach a certain threshold.
Toronto Mayor Olivia Chow said the city is working to avoid further pool closures by deploying additional lifeguards and medical staff to pool sites.
"Pools need to be open during a heat wave. That's obvious to us all," Chow said in a social media post. "We're fixing it now."
The Toronto District School Board, meanwhile, warned of "uncomfortable conditions" in its schools due to the extreme heat, advising students to wear light clothing, hats, sunscreen and to drink lots of water.
"Across the TDSB, while some schools are fully air conditioned and some are partially air conditioned, others have no air conditioning and the extreme heat will result in uncomfortable conditions," the school board said in an email to parents on Sunday.
The email said closing schools due to extreme heat "is not an action typically taken by TDSB or other school boards across the province."
However, several French-language schools in the province, including some in Toronto, were closed Monday due to a lack of air conditioning, the Viamonde School Board said on its website.
Meanwhile in Quebec, the Montreal school services centre, which represents French schools in the city, said the local public health department did not recommend shutting down classes. Instead, activities would be adjusted according to the heat, it said.
In Old Montreal, Beverly Iron and David Mudge from London, England, said they changed their vacation plans due to the heat. After the temperature climbed to 34 C, with a humidex of 45, the pair opted out of a long walk in favour of sitting under the trees overlooking the St. Lawrence River with a couple of vanilla ice cream cones.
“It’s hit us hard,” Iron said.
Next to a nearby fountain and artificial lake in Montreal, B.C. couple Peter and Cindy Martin were watching their West Highland terrier, Fergus, roll happily in the grass after a quick swim. The couple said they felt comfortable after drinking plenty of water, but had worried about their pet.
“He was just panting, he was hot,” Peter Martin said, noting with a smile that the no swimming signs “don’t show any dogs not swimming.”
Some Ontarians are trying to beat the heat by heading to beaches such as those at Sibbald Point Provincial Park, on the shore of Lake Simcoe roughly 70 kilometres north of Toronto.
Dmytro Allot, who moved to Canada two years ago from Ukraine, said this is his first time experiencing extreme heat in Canada.
"Sometimes we had this weather (in Ukraine), but it's not normal for us to have such a high temperature," Allot said.
Carter Carino, who drove an hour from Toronto to get to Sibbald Point, said he came armed with five bags of ice and Gatorade to stay cool.
"I just wanted to hang out at the beach, trying to stay hydrated, get a lot of electrolytes in," he said.
Public health officials are encouraging everyone in the heat zone to drink plenty of water and be on alert for early signs of heat exhaustion.
Overnight lows are forecast to stay between 22 to 25 C, with the humidex above 30 degrees, until the expected mid-week cool down.
--With files from Morgan Lowrie and Vanessa Tiberio
This report by The Canadian Press was first published June 23, 2025.
Natasha Baldin, The Canadian Press
