Extreme Heat

Credit: Justa Jeskova

The extreme heat event of 2021 is a stark example that our climate is changing, and we must prepare for the expectation that these events will become more frequent, longer, and hotter in the decades ahead.

Early in the summer of 2021, we experienced an unprecedented extreme heat event that tragically led to the deaths of hundreds of people in British Columbia. Temperatures were at least 15°C higher than usual across the entire province, but some areas and some people were affected more than others.

New evidence shows that sustained ambient temperatures over 31°C can overwhelm the body’s natural cooling systems, especially for older people and those who have chronic health conditions.

Higher average temperatures lead to a higher likelihood of Extreme Heat. An Extreme Heat Emergency is when daytime and nighttime temperatures get hotter every day and are well above seasonal norms.

According to the Provincial health officer, those at higher risk during extreme heat include:

  • Seniors aged 65 and older
  • Those marginally housed
  • Vulnerable people who live alone
  • people who work in hot environments
  • people who are pregnant
  • infants and young children
  • people with limited mobility
  • people with substance use disorders
  • people with pre-existing health conditions such as diabetes, heart disease or respiratory disease

During an extreme heat emergency

  • When a heat emergency is declared, you can expect a Broadcast Intrusive alert to your mobile device from the Province of BC, similar to the alerts already used for Amber alerts and tsunami, wildfire and flood warnings.
  • Seek refuge at the Whistler cooling centres if you do not have air conditioning.  Hours of operation will be posted at whistler.ca.
    • Whistler Public Library
    • Meadow Park Sports Complex
  • Remain hydrated.  Drink water throughout the day even if you are not thirsty. Find a map of Whistler’s drinking fountain locations here.
  • Continue to monitor the media and Environment Canada for updates.

Preparing for an extreme heat emergency

Heat events, also known as heatwaves, are a series of days that are hotter than normal temperatures for the region. 

Heat events can affect anyone’s health, but extreme heat can pose a very high risk of severe illness for some people if they do not have access to a cool indoor environment. Heat can build up indoors when the outdoor temperatures are climbing every day, and the situation can become dangerous. The longer the heat lasts, the more dangerous it becomes.


BC Heat Alert and Response System 

The Province is launching the BC Heat Alert and Response System (BC HARS) to help ensure communities and local governments have the tools they need to stay safe during heat events.

Under BC HARS, the Province is prepared to issue a Broadcast Intrusive alert for extreme heat emergencies.

The Province is also bringing in additional measures to bolster B.C.’s ambulance system to better respond to a significant increase in 911 calls during a heat emergency.

BC HARS includes two categories of heat events: heat warnings and extreme heat emergencies. In the event of a heat warning or extreme heat emergency, the provincial government and local authorities will take appropriate actions based on their individual heat plans and processes.

The criteria for the BC Heat Alert and Response System are as follows:

Heat warning

  • Two or more consecutive days in which daytime maximum temperatures are expected to reach or exceed regional temperature thresholds and nighttime minimum temperatures are expected to be above regional temperature thresholds
  • A moderate increase in public health risk

Extreme heat emergency:

  • Heat warning criteria have been met and daytime maximum temperatures are expected to substantively increase day over day for three or more consecutive days
  • A very high increase in public health risk

For extreme heat emergencies, the Province is prepared to issue alerts through the national public alerting system, Alert Ready, which is already used to issue Amber alerts and tsunami, wildfire and flood warnings.

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