But a cold front should pass through on Friday, making conditions more comfortable.
"My thoughts are with the loved ones of those who have died in Quebec during this heat wave", Prime Minister Justin Trudeau said on Twitter.
The recent heat wave has plagued central Pennsylvania with highs well into the 90s. "However the daytime highs are still expected near 30 and overnight lows in the high teens", Environment Canada said Monday.
In the Eastern Townships region southeast of Montreal, four deaths are under investigation to determine if they are related to the extreme heat.
An extended heat warning issued by the city's medical officer of health on Sunday remains in effect. Cool down is expected by Friday with the passage of a cold front. The risks are greater for young children, pregnant women, older adults, people with chronic illnesses and people working or exercising outdoors.
"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.
For people experiencing homelessness, the city said TTC tokens are available at several drop-ins throughout the city to be used to get to cool places.
Canada Day was supposed to start out sunny in the morning, turning to a mix of sun and cloud in the afternoon, with a 30 per cent chance of showers.
University of Waterloo climate scientist Blair Feltmate says the heat wave can't be directly attributed to climate change, but that suggesting the two aren't linked would be like arguing that no particular home run can be attributed to steroids when a baseball player on a hitting streak is caught doping.
Even those not specifically at risk are encouraged to stay inside or in the shade, and to limit outdoor activity in the heat.