Heat and extreme heat
Environment Canada issues "heat alerts” when the temperature reaches 30 °C and the humidex (temperature and humidity combined into one number to reflect the perceived temperature) reaches 40. The main effect of heat on the population is discomfort.
The term "extreme heat" has been defined by public health authorities to plan for heat events as a means of foreseeing heat episodes that are likely to have an impact on the health of vulnerable individuals. In Montréal, an "extreme heat" episode is defined as three consecutive days when the average maximum temperature reaches 33 °C and the average minimum temperature does not drop below 20 °C, or when the temperature does not drop below 25 °C for two consecutive nights. Environment Canada does not issue extreme heat alerts, but its weather forecasts are used to anticipate situations which could cause health problems.
Source: Direction de santé publique (DSP) of the Agence de la santé et des services sociaux de Montréal
Did you know?
- When it's very hot, some people are at greater risk of developing heat-related health problems. Older people, young children, people with heart or lung disease, and people with mental health problems can be affected more than the rest of the population.
- There have been at least five extreme heat episodes in the Montréal region since the 1980s.
- The main health problems linked to heat are the following: dehydration, headaches, dizziness, confusion, fainting.
- If these symptoms are present, call Info-Santé at 8-1-1 or talk to a health professional.
- If you have fever in addition to these symptoms, you may have heatstroke, which is an medical emergency. In this case, call 9-1-1 to get help.
Are you a health professional?
If you are interested in learning more on this subject, read the extreme heat fact sheet on the website of the Director of public health for the Montréal region (website in french only).
Everyone should take precautions during heat or extreme heat episodes, but some people are more at risk than others, namely:
- elderly people
- people suffering from chronic diseases such as diabetes or cardiovascular, respiratory or neurological diseases; and
- 0- to 4-year-old children.
What can you do to prevent problems and protect yourself?
When it is very hot, you need to:
- spend a few hours a day in a cool and preferably air-conditioned place;
- drink a lot of water, without waiting to be thirsty; and
- reduce your level of physical exertion.
The families and friends of elderly people and of people with chronic diseases or mental health problems should check in on them regularly during heat waves to make sure that they are taking the recommended preventive measures and to give them any help they may need.
Elderly people can learn what they should do during periods of heat or extreme heat, by reading the "Heat Wave Be cautious!" leaflet PDF 450 KB (available in French under the title "Canicule Attention!")
Information on heat episodes is also available in other languages. Click on the language of your choice to download the documents:
Documents for seniors in various languages:
People with mental health problems
People with mental health problems can also follow protect themselves against the heat by following the advice given by the Douglas Institute in the flyer “There Is a Heat Wave!”. For more information: Heat and Mental Health.
Children in the 0 to 4 year-old group
Children in the 0 to 4 year-old group are also very vulnerable during heat waves. To find out what the recommended precautions are, see the "It’s really hot!" leaflet 140 KB PDF file ("Il fait très chaud!" in French).
Documents in various languages for parents and caregivers of children aged 0 to 4 years (140 KB PDF files):
Whom should you contact to get help?
Where can you find additional, credible information?
Information for Montréal region employers and employees, especially in the construction industry and municipal services
Any kind of work done in hot weather exposes workers to health risks, and the risks are greater during the first days of a heat wave. Our bodies take time to adjust to a rise in temperature, and all the more so if we have to perform demanding physical tasks, at a sustained pace in a place that is poorly ventilated or exposed to the sun. Preventive measures must be taken depending on the circumstances.
In addition to drinking a lot of water and covering yourself lightly to protect yourself from heatstroke, you can get useful tips from the CSST on heatstroke and how to prevent it (in French only), especially when you are working. You'll also learn how to recognize the first signs of heatstroke and what to do if a colleague or employee starts feeling ill.
Whom should you contact to get help?
- In the event of a malaise, call a doctor or check with Info-Santé at 811.
- In case of an emergency, call 911.
- If you are a worker, contact the occupational health team closest to you:
- CSSS de la Montagne - 6600 Côte-des-Neiges Road, 5th floor, Montréal (Québec), H3S 2A9 - Tel.: 514 731-1386 ext. 8652, Fax: 514 739-8132
- CSSS Jeanne-Mance - 5800, Saint-Denis Street, Room 1002, Montréal (Québec,) H2S 3L5 - Tel.: 514-858-2460, Fax: 514 858-6568
- West Island Health and Social Services Centre - 1405 Transcanada Highway, 5th floor, Montréal (Québec), H9P 2V9 - Tel.: 514-421-5750, Fax: 514 421-5779
- CSSS de la Pointe-de-l'île - 13926, Notre-Dame Street East, Montréal (Québec), H1A 1T5 - Tel.: 514-642-2121, Fax: 514-642-1684