Environment Canada has issued a high heat and humidity warning for Montreal and surrounding areas in southern Quebec.
The Montreal public health agency is advising people to spend at least a few hours a day in a cool, ideally air conditioned location like a movie theatre or a shopping mall.
The agency also recommends that people drink plenty of water throughout the day and reduce their level of physical activity.
Checking on older people and children, particularly those who suffer from health problems, is also a good idea, the agency says.
In Montreal, temperatures are expected to stay above 30 Celsius for at least the next four days.