Environment Canada issued a heat warning for southern Quebec on Friday as daytime high temperatures may hit 31°C in Montreal on Friday and 33°C on Saturday.
With the humidity it will feel more like 41°C to 45°C on Friday and Saturday, and while the temperature will drop slightly on Sunday it will stay exceedingly muggy.
"Overnight lows expected to be in the 20s so we're not expected to get much relief," said CTV weather specialist Lori Graham.
"Not only are we dealing with heat and humidity coming up from the U.S. but we're also dealing with the remnants of Barry so a lot of tropical moisture headed up in our direction."
Because the temperature is likely to be 29°C on Sunday, even if the humidity makes it feel worse, this will not officially qualify as a heat wave.
Meteorologists define a heat wave as three or more days where the daytime high is 30°C or more, and overnight lows are more than 20°C.
During hot spells authorities advise people to drink plenty of water, to stay indoors in cool locations, and to reduce physical activity.
They also want people to check on loved ones and neighbours, especially those who have mobility limitations, live alone, or have a chronic illness.
Children, the elderly, and those doing physical work outside are the most at risk.
They also warn to never leave people or animals inside parked vehicles.
The Montreal public health department has a plan it can enact for extreme heat waves and it has yet to do that this summer.
In the event of a heat emergency, pools will be open longer, people without air conditioning at home will be encouraged to visit buildings where the climate is controlled, and health workers will expect to deal with more calls than usual.
Last year more than 60 people died during one heat wave in Montreal, most of them over the age of 65 and with a chronic illness.
