Heat

What is a heatwave or heat episode?

Environment Canada issues extreme heat warnings when the forecasted temperature is expected to reach or exceed 30°C and the humidex index is expected to reach or exceed 40. The entire population must take precautions to prevent the harmful effects of heat on health.

A heatwave or heat episode is characterized by an extreme heat event lasting at least three consecutive days with particularly high temperatures (>30°C) and a reduced range between daytime and nighttime temperatures

Heat and its alert levels

See the table (in french only)

Effects of heat on health

• Headaches
• Muscle cramps
• Small red bumps on the skin (heat rash)
• Unusual fatigue or heat exhaustion
• Swelling of hands, feet, and ankles
• Nausea or vomiting
• Signs of dehydration:
  • Severe thirst
  • Dark urine
  • Dry skin
  • Fast pulse and breathing
  • Decreased need to urinate

If you feel unwell or have questions about your health, call Info-Santé at 811 or consult a healthcare professional. In case of emergency, call 9-1-1.

The most common indirect effect is the worsening of a chronic illness, such as cardiovascular, respiratory, renal, neurological diseases, and diabetes.

In case of an exceptional heatwave that is likely to impact the health of vulnerable people, the CIUSSS implements its regional emergency measures plan in collaboration with its partners (hospitals, municipalities, civil protection, etc.) to protect public health.

How to prevent the effects of heat?

• Stay well hydrated
  • Drink plenty of water without waiting to feel thirsty
• Avoid consuming alcoholic beverages, as alcohol can worsen dehydration
• Cool down often in air-conditioned or shaded places:
  • Take a shower, a cool bath, or swim in a safe and accessible pool or water body.
• Reduce outdoor physical efforts, especially between 10 AM and 3 PM.

For more recommendations and tips to protect yourself from the effects of heat, click here.

For the population, the most at-risk situations related to extreme heat occur:

• During the first heatwaves, as the body is not accustomed to it;
• When it is very humid and there is no wind;
• If high temperatures persist for several days or continue at night;
• If living in downtown areas where heat is more intense;
• If living in an environment without air conditioning;
• When engaging in sports;
• If working manually outside or in a hot environment.

Exercise increased vigilance with vulnerable individuals:

• Infants and young children;
• Elderly people;
• People with chronic diseases,
• People with mental health problems, or those taking medications.

Main recommendations during extreme heat:

• Stay well hydrated: drink before feeling thirsty, at least 4 glasses of water or juice per day;
• Stay cool: spend at least 2 hours a day in an air-conditioned or cool place;
• Reduce physical efforts: whether in sports or at work.

Precautions for children

During extreme heat, the health condition of a child under 5 years old can deteriorate rapidly. See the tips to follow and signs to watch for by clicking here.