Oppressive or extreme heat

Oppressive heat is characterized by temperatures of 30 °C or higher and a humidex (combined impact of heat and humidity) of 40 or more. The definition of extreme heat varies by region. On average, the temperature must be between 31 and 33 °C during the daytime and between 16 and 20 °C at night for 3 consecutive days.

Oppressive or extreme heat can cause drought and forest fires. It is a danger to public health, especially for people at risk.

Follow prevention tips

To reduce risks during periods of oppressive or extreme heat, avoid overheating, which puts a strain on the body and can affect your health. Here are some recommendations:

  • Wear light clothing.
  • When you are outdoors, take shelter under a parasol or wear a wide-brimmed, well-ventilated hat.
  • Apply sunscreen to limit your exposure to ultraviolet rays.
  • Limit physical activity, especially in the middle of the day, when it is hottest.
  • Drink plenty of water (6 to 8 glasses of water a day for an adult).
  • Avoid alcoholic beverages.
  • Spend at least 2 hours a day in a cool air-conditioned place (library, shopping centre, etc.
  • Take at least one cool shower or bath daily or refresh your skin with a wet towel several times a day.
  • Close the curtains and blinds to keep your house cool.
  • Open all windows in the evening, if it is cooler outside.
  • Use the air conditioning to lower the temperature in your home more quickly.

During periods of oppressive heat, the health of babies and children can deteriorate fast. Find out what precautions you can take to protect babies and children from the effects of this type of heat. Never leave a baby or child alone in a car or a poorly ventilated room, even for a few minutes.

You can offer to help your loved ones, especially if they live alone, are losing their autonomy or are vulnerable to heat.

Your pets can also suffer from the heat (in French only). Avoid leaving them in the sun and give them water to keep them hydrated.

Pay attention to air quality during periods of oppressive or extreme heat, as heat may contribute to the formation of smog. Check the air quality index in your area.

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Monitor symptoms and take action

Monitor symptoms related to the effects of oppressive or extreme heat on health.

If your condition or that of a loved one worsens or if you or a loved are vulnerable to heat, contact Info-Santé 811 to obtain medical advice. In a medical emergency, call 911 or go to the nearest hospital.

Some workers must be particularly careful and take recommended precautions to prevent heat stroke (in French only).

Follow the instructions that authorities give you

Obey restrictions on access to the forest, as well as on travel, work or burning in the forest during heatwaves. Beware of dry vegetation, including that found in your garden. Adhere to bans on open fires and find out about the precautions to take and the safety rules to follow in the event of a forest fire.

Know what to do after a disaster

Consult the After a disaster section to learn instructions and recommendations for getting back to normal in a safe manner.

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