Environment Canada issued a smog warning as "high concentrations of pollutants are expected to persist through the night".
The heat wave began on June 29, but, one week later, relief is in the forecast.
Temperatures soared to 93 Fahrenheit with a humidity that made it feel much hotter than that, the meteorological service said.
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So far 132 civilians, including 25 children, have been killed in the latest surge in fighting in Daraa, according to the Observatory.
Most of the victims linked to the "overwhelming heat" were in the Montreal area, which recorded 28 fatalities, metropolitan health authorities told AFP in an email.
So far, 18 of the 33 deaths have been in Montreal, the most populous city in the province, with other deaths in surrounding regions.
In Ontario, a spokeswoman for the coroner's office said it couldn't confirm if there were any heat-related deaths, adding it could take weeks or several months to complete such probes.
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We understand and share her desire to see the immediate release of children from detention and reunion with their parents. In February a year ago , protesters hung a giant "Refugees Welcome" banner across the Liberty statue's observation deck.
The temperature is set to rise again in Montreal by the end of the weekend, however, with the humidex expected to reach up to 36 C for Sunday and Monday.
"We go out to the paramedics, we go out to the hospitals and we ask them to make sure to identify any deaths they believe are related to heat and that allows us to intervene more quickly", Kaiser said.
Meanwhile, a unsafe heat wave is expected to grip California and parts of the southwest Friday and into the weekend, threatening millions of people and likely fueling existing wildfires in the United States.
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The Paris Saint-Germain forward has been slated, especially in Britain, for diving and exaggerating fouls during the tournament. The biggest sports tournament in the world comes with some of the most heartbreaking moments for fans and players alike.
To help residents, the city introduced a plan of emergency response, which includes the extension of the public swimming pools, free distribution of water and bypass the firefighters vulnerable categories of citizens.