Toronto remains under a heat warning issued by Environment Canada for the second day in a row.

Arnold Ashton, severe weather meteorologist for Environment Canada based in Toronto, said the warning originally issued on Friday has been extended into Saturday. The temperature is expected to reach a high of 32 C, while the humidex will make it feel like 39 C. The warning will likely remain in place on Sunday.

"It's a warm, muggy day across the region," Ashton said. "It's a pretty warm, toasty regime that we are under."

Hot, humid weather is in the forecast for Monday and Tuesday as well. A ridge of high pressure now over the region has brought the extreme heat, he said. Slightly cooler weather is expected later on Wednesday. Temperatures on Thursday and Friday are expected to be normal, with highs around 19 C.

As of noon on Saturday, a 1959 temperature record of 30.6 C was broken at Toronto's Pearson International Airport, when the mercury reached 31 C. 

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Diners eat lunch on a shaded outdoor patio downtown. The city remains under an Environment Canada heat warning issued on Friday. (Muriel Draaisma/CBC)

Ashton said the warning is a heads-up for people at risk of heat-related illnesses, cautioning them that it could become uncomfortable. 

Extreme heat can be 'troublesome'

Extreme heat can pose risks for young children, pregnant women, older adults, people with chronic illnesses, people working or exercising outdoors, those with limited mobility or certain mental health issues, people taking medications and the homeless, according to the city.

"We're not used to this type of heat," he said. "It just troublesome for some people."

In the summer, Ashton said Toronto had changeable conditions, with the occasional warm day. Now, however, the city is enjoying more than one sunny day in a row, what he called "prolonged warmth."

"What's making it different this time here in mid to late September, we're on roughly day 11 or 12 of a string of beautiful, sunny, summerlike conditions, thanks to a high pressure ridge that is basically parked across the area," he said. "We're basically getting our summer now."

The projected high for Sunday is 31 C with a humidex value of 40 C. "Ample" sunshine is forecast for Monday and Tuesday. He said the temperature early in the week may be "a hair or two below what we have been getting."

Dr. Eileen de Villa, Toronto's medical health officer, also issued a heat warning for the city on Saturday.

During a heat warning, members of the public are encouraged to visit family members, friends and neighbours, especially isolated adults and seniors who are at greater risk of heat-related illness to ensure they are drinking fluids as well as keeping cool.

Toronto Public Health said in a news release that it issues heat warnings when high heat or humidity is expected to last two or more days.

The warnings are intended to remind residents how to beat the heat. They also trigger the opening of the city's cooling centres, air-conditioned places where residents can rest indoors. 

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A dog cools off in a swimming pool. Toronto Public Health also issued a heat warning for the city on Saturday. (iStock)

De Villa said people should keep cool in air-conditioned public places, including shopping malls, libraries and community centres. For homeless people, there are 50 available drop-in centres.

Seven locations in Toronto have an air-conditioned place where residents can rest indoors, receive a cool drink and light snack. They are:

  • Metro Hall, 55 John St. (24 hours)
  • East York Civic Centre, 850 Coxwell Ave. (11 a.m. to 6 p.m.)
  • North York Civic Centre, 5100 Yonge St. (11 a.m. to 6 p.m.)
  • Driftwood Community Centre, 4401 Jane St. (11 a.m. to 7 p.m.)
  • Etobicoke Civic Centre, 399 The West Mall (11 a.m. to 6 p.m.)
  • McGregor Community Centre, 2231 Lawrence Ave. E. (11 a.m. to 7 p.m.)
  • Centennial Community Centre, 1967 Ellesmere Rd. (11 a.m. to 7 p.m.)

On weekdays, the community and civic centres are open until 7 p.m., while on weekends, the civic centres are only open until 6 p.m.

Over the weekend, staff who are trained to help residents affected by extreme heat will be on hand at the seven locations.