During a heat wave, people can quickly experience health problems. Throughout the summer, Montréal keeps a close watch on the situation, activating its response plan as soon as weather forecasts include:

• a temperature that stays at or above 33°C (cumulative average) during the day and does not go below 20°C at night, for three consecutive days 
• a temperature at or above 25°C for two consecutive nights

Extended opening hours for swimming pools, wading pools, play fountains and beaches, as well as a number of air-conditioned public buildings are provided so that people can cool off.

The city works with the Centre-Sud-de-l’Île-de-Montréal CIUSS (Centre intégré universitaire de santé et de services sociaux) to make sure that the most vulnerable people are safe.

The following people are most at risk during a heat wave:

• Children under 4
• People aged 65 and over who do not have air conditioning
• People chronically ill with diabetes or cardiovascular, cerebrovascular, respiratory or neurological illness
• People experiencing mental health problems (especially schizophrenia) or problems of alcoholism or drug addiction
• People living alone and experiencing reduced autonomy
• Workers or athletes involved in strenuous physical activity