Many cities in Ontario and Quebec are officially experiencing heat waves after three consecutive days of 32 C or higher temperatures.
This is Toronto's first heat wave since 2007.
Health officials in both provinces were urging people to try to keep cool in the scorching temperatures and high humidity. Temperatures in Toronto and Montreal hit a high of 33 C on Tuesday, while the mercury hit 34 C in Ottawa and almost 35 C in Windsor.
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Temperatures in the 30 C range, which feel more like the 40s when humidity is factored in, are forecast again for some areas on Tuesday and Wednesday.
The hot weather is expected to linger until the end of the week when a cold front moves in, CBC meteorologist Johanna Wagstaffe said.
The heat wave is not unusual from a climate standpoint, Environment Canada's senior climatologist, Dave Phillips, told CBC News.
"We're known as the steam bath capital of Canada in southern Ontario. Just the fact that it's been two summers where we didn't have this kind of weather. We always had short memories when it comes to the weather," he said, pointing to "torrid" heat waves in 2007 and 2005.
The humidity makes it feel even hotter, Phillips said.
"All that humidity, it's tropical air, Gulf of Mexico air," he said. "All that air we got in June is now getting into the atmosphere from the lakes and wetlands. You can almost cut the air, it is so humid."
Get used to the hot weather, which is sticking around for the next 30 days, though not necessarily every day, he added.
"We said this was going to be a warm summer … [from] mid-July to mid-August, most of the holidays and people are looking forward to it," Phillips said. "Across the country in Vancouver Island to the Bay of Fundy and beyond, we'll see warmer-than-normal conditions."
As for precipitation, it will be near normal for most of the country — wetter than normal in the east and drier in the far west, he added.
Cooling centres opened
Toronto opened eight cooling centres across the city Tuesday to help people cope with the heat.
Toronto's medical officer of health and the city's Emergency Medical Services urged the public and landlords to check on elderly or isolated tenants and neighbours.
"We know that prolonged extreme heat conditions can be fatal for people with chronic health conditions and for seniors," Dr. David McKeown said in a statement.
"If you own or operate a rooming house or apartment building, it is your civic duty to check on residents who are vulnerable, especially if they do not have air conditioning. As these conditions continue without relief, early interventions will save lives."
Infants and people taking medications for mental health, heart conditions or blood pressure are also at risk as these medicines may affect patients' ability to cope with extreme heat, McKeown said.
Officials in Ottawa opened public buildings with air conditioning for members of the public who need to go somewhere cool, and health officials warned people to watch for symptoms of heat stroke and heat exhaustion.
"When you start feeling thirsty, take action. Cool yourself down, hydrate yourself and eat," said J.P. Trottier, a spokesman for the Ottawa paramedic service.
"If you start overheating a bit, feeling dizzy or nauseated, it's time to take action — you do not want it to progress into heat stroke."
Chris Grant, deputy chief of Essex Windsor Emergency Medical Services, said people don't necessarily need EMS service if they've been in the sun too long. Grant told CBC News if someone is feeling the effects of heat exhaustion, the first thing to do is get that person into the shade.
"Even if they're outside, get them to a tree. If they can get them to a home that's air-conditioned, that helps tremendously.… Give them fluids as long as they're conscious and able to swallow."
In Montreal, public health officials are reviewing temperature and weather data to determine whether the city needs to open cooling shelters. Some pools and libraries may extend their hours to give people a respite from the searing temperatures.
In the meantime, Norman King, a spokesman for Montreal public health, suggests that people drink lots of water, seek cool places and diminish the intensity of outdoor activity to beat the heat.
In Windsor, Ont., the thermometer hit 34.6 C, almost breaking the record of 35.3 C set in 1988.
Alek Ahmedi and his family came to Windsor on holiday from Florida.
"We came up here for vacation to feel a little cooler air but I don't know what happened here," said Ahmedi as he strolled Windsor's riverfront. "It's as hot as over there now, but it's not bad, it's breezy and everything."
Gilles Germain and his family were also on holiday in Windsor from Montreal, and thought they'd head to Sandpoint Beach to cool off, only to find it closed because of E. coli contamination.
"I'm going to stay here a little bit and see if the kids can have some fun and refresh themselves. That's the main point to get refreshed."
The worst heat wave in Ontario was in July 1936, when temperatures hit 42.2 C in Atikokan and Fort Frances, according to Environment Canada.[GALLERY id=3658 cat=canada]