TORONTO — Dangerously high temperatures persisted on Monday across much of Ontario and southwestern Quebec, as a heat dome lingers over the region.
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 expected to linger between 42 and 46 C.
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 14,000 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."
Temperatures in Toronto are expected to reach 36 C on Monday, Environment Canada said, with the humidex making it feel like 46 degrees.
The Toronto District School Board is warning 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.
The high temperatures are expected to affect communities from southwestern Ontario and north to Sudbury and Timmins.
In Quebec, the hottest temperatures are expected to be felt from Montreal to Shawinigan and north to Abitibi.
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.
--With files from Vanessa Tiberio
This report by The Canadian Press was first published June 23, 2025.
Natasha Baldin, The Canadian Press
