top of page

Extreme Heat

Preparedness Series

Now designated as the leading cause of illness and death from weather-related hazards in Canada, preparing for extreme heat and heat waves has proven to be supremely important.

Extreme Heat and Heat Waves

As temperatures continue to rise with extreme heat season fast approaching, the topic of heat illness prevention becomes a top priority. 


The importance of heat illness prevention is made further apparent now that the Government of Canada has determined that extreme heat is the leading cause of illness and death from weather-related hazards in Canada.


There is no example of the adverse effects heat waves cause that is more fresh in the minds of British Columbians than the June-July 2021 fire near the village of Lytton, which saw 90% of the village burned down and forced the evacuation of nearby Nlaka’pamux Nation Tribal Council (NNTC) communities. 


During this period, the hottest temperature ever recorded in Canadian history was taken in Lytton, B.C. (49.6℃ on June 29, 2021). This same heat wave also killed over a billion sea creatures as water temperatures reached all-time highs.

It is a commonly accepted theory that the recent influx of extreme heat warnings is influenced by climate change, and that heat waves will become even more common as our planet becomes increasingly warmer. Last May, Western Canada experienced another period of extreme heat which placed many communities under extreme heat warnings and broke many longstanding temperature records. The summer of 2023 was also the hottest summer ever recorded on Earth according to researchers from NASA’s Goddard Institute of Space Studies (GISS).





Map depicting the land surface temperature on June 29, 2021 (Flickr @European Space Agency/Photo)

What is 'extreme heat'

A period of extreme heat is often referred to as a heat wave, however there is no commonly accepted definition of either term. In Canada, we can loosely define extreme heat and heat waves as a period of at least two days in a row where temperatures reach over 30℃. We use this because 30℃ is considered a “hot day” in Canada, and these hot days increase the likelihood of heat-related emergencies.


Heat waves generally form when air becomes trapped in our atmosphere. Instead of constantly circulating in and out, the air remains stagnant and heats up like the air inside of an oven. Heat waves can occur with or without high humidity.


When in extreme heat, your body must work harder to maintain a normal temperature, which can have fatal consequences. Extreme heat can cause heat cramps, heat exhaustion and heat stroke, as well as worsen pre-existing medical conditions like kidney or lung disease. Those that are most vulnerable to extreme heat are seniors, young children, pregnant women and people with acute or chronic health conditions. 


The effects of heat can be exacerbated in cities due to the urban heat island (UHI) effect. Non-urban communities can also be severely disrupted during and after periods of unusually hot weather, and heat disasters in non-urban communities present a completely different set of challenges. 

Heatwaves also burden health and emergency services and increase the strain on water, energy and transportation which results in power shortages or even blackouts. Food security may also be strained if people lose their crops or livestock due to extreme heat.

What to do:

Here are some ways you can prepare for B.C.'s next heat wave


  1. Emergency cooling centers or cooling spaces may be listed on EmergencyMapBC. If not listed, contact your local government or band office.

  2. Current fire bans and restrictions can be found on the BC Gov website.

Stay in the shade

When outside, try to seek shady areas as much as possible or take a break in a shady spot. Temperatures in the sun can be 10-15℃ higher than perceived. 


Only use electric fans when temperatures are below 40℃

In temperatures above 40℃, electric fans will circulate the hot air and heat the body.


If you are using Air Conditioning, turn your thermostat to 27℃ and turn on an electric fan when out of the house

Heat flows from hot environments to cool ones and when you set your thermostat to a higher temperature, hot air enters your home at a lesser frequency. Alternatively, when you leave thermostat at a very cool temperature all day, your AC is forced to work harder to account for the increase of heat entering the home. Leaving an electric fan on near AC vents will help circulate that cool air throughout the house, making areas of the home feel cooler than they are. Not only will this trick continue to cool your home, it can also save up to 70% on your electricity bill for cooling. 


Drink water regularly

Ideally aiming for 1 cup of water per hour, around 2-3 liters per day. 


Regularly check-in with the elderly and vulnerable people in your circle

The British Columbia Center for Disease Control (BCCDC) confirmed a 100% increase in deaths among adults aged 50 or older during the 2021 heat dome.


Don’t cover an infant's stroller with dry fabric

This will not shade the child, it will heat the carriage up even more. Instead use wet, thin fabric and re-wet when necessary. Pair this with a portable fan for even greater cooling. 


Turn on your kitchen exhaust fan

The exhaust fan found standard in kitchens will suck the hot, humid air from the room. The exhaust fans in your bathroom work in the same way as well. 


Create a cross breeze

You can create a cross breeze by setting up two electric fans to blow cool air in and pull away hot air. 


1 . “Surviving the heat: The impacts of the 2021 western heat dome in Canada.”, Government of Canada, 26 June 2022,


2. Uguen, Eva, and Bethany Lindsay. “For 3rd straight day, B.C. village smashes record for highest Canadian temperature at 49.6 C.” CBC, 30 June 2021,


3. Lynch, Laura. “The 2021 heat dome in B.C. had wide-ranging impacts on marine life, scientists say.” CBC, 23 June 2022,


4. “NASA Announces Summer 2023 Hottest on Record – Climate Change: Vital Signs of the Planet.”, NASA, 14 September 2023,

bottom of page