OTTAWA, ON, Sept. 17, 2025 /CNW/ - Environment and Climate Change Canada is exploring how weather events—like heat waves, floods, and wildfires—are impacted by human-caused climate change. By understanding how our warming environment affects the strength, frequency, and risks of extreme weather, Canadians can make informed decisions that protect the health, safety, and long-term well-being of our communities.

Canadian climate scientists recently analyzed ten of the hottest heat waves that impacted the country in July and August of 2025, using the Rapid Extreme Weather Event Attribution system. The system continuously monitors for extreme heat and extreme cold events across Canada.

The system shows that of these heat waves, nine were made much more likely because of climate change. This means that human influence on the climate made the following heat waves at least 2 to 10 times more likely to occur:

Alberta (August 25 to August 31)

• Peak daily high temperature during the heat wave: 28.8 °C*
• Degrees above normal daily high temperature: 9.3 °C

Fort Smith, Northwest Territories (August 24 to August 31)

• Peak daily high temperature during the heat wave: 25.5 °C*
• Degrees above normal daily high temperature: 11.6 °C

Southern British Columbia (August 23 to September 7)

• Peak daily high temperature during the heat wave: 27.0 °C*
• Degrees above normal daily high temperature: 10.0 °C

Northern British Columbia (August 23 to September 9)

• Peak daily high temperature during the heat wave: 23.5 °C*
• Degrees above normal daily high temperature: 9.7 °C

Southern Quebec (August 7 to August 13)

• Peak daily high temperature during the heat wave: 29.3 °C*
• Degrees above normal daily high temperature: 9.1 °C

Northern Quebec (August 6 to August 9)

• Peak daily high temperature during the heat wave: 23.8 °C*
• Degrees above normal daily high temperature: 7.0 °C

Fort Smith, Northwest Territories (July 30 to August 1)

• Peak daily high temperature during the heat wave: 25.2 °C*
• Degrees above normal daily high temperature: 6.0 °C

Atlantic Canada (July 10 to 15)

• Peak daily high temperature during the heat wave: 25.6 °C*
• Degrees above normal daily high temperature: 7.1 °C

Northern Quebec (July 10 to 13)

• Peak daily high temperature during the heat wave: 24.2 °C*
• Degrees above normal daily high temperature: 7.5 °C

In August, a heat wave in Atlantic Canada was made far more likely because of climate change. This means that human influence on the climate made this heat wave at least 10 times more likely to occur:

Atlantic Canada (August 7 to August 14)

• Peak daily high temperature during the heat wave: 28.4 °C*
• Degrees above normal daily high temperature: 9.6 °C

^*Averaged over the region

The system uses climate models to compare today's climate to a pre-industrial one and demonstrate how CO2 and other emissions from human activities increase the chances of some extreme weather events while decreasing the chances of others. Some events, like heat waves, are happening more frequently because of climate change. Other events, like extreme cold, are happening less and will be rarer in the future. The system shows that the heat waves experienced in these regions during July and August would have been rare in a pre-industrial climate.

This past winter, scientists began analyzing the connection between human-caused climate change and extreme cold temperature events. They will begin analyzing extreme precipitation events later in 2025. As with extreme hot events, human influence on the climate increases the likelihood of extreme precipitation events (for example, heavy rainfall).

Prolonged heat waves and longer fire seasons are major contributors to more frequent and intense wildfires across Canada. Extreme heat dries out forests and vegetation, which become fuel that can ignite and spread wildfires.

The 2023 wildfires in Canada burned almost 15 million hectares of forest and cost Canadians tens of billions of dollars in damages. 2025 is already the second worst wildfire season in Canada in terms of area burned.

Canadians are urged to regularly monitor weather forecasts, take all weather alerts seriously, and get prepared for weather-related events by developing an emergency plan and being ready to adjust their travel plans. Canadians can download the WeatherCAN app to receive weather alert notifications directly on their mobile devices. Alerts help Canadians prepare to face severe weather events, save lives, and reduce the impacts on property and livelihoods.

Quick facts

• The Rapid Extreme Weather Event Attribution system uses climate models to compare two different climates: the climate of the 1800s, based on levels of atmospheric gases that existed before the Industrial Revolution; and the climate of today, based on observed levels of greenhouse gases and other results of human activity.
• In Canada, wildfire season is generally from May to September. The wildfire seasons for 2025, 2024, and 2023 are among the top 10 on record in terms of area burned (source).
• Environment and Climate Change Canada is the country's official source for weather information and severe weather warnings and is committed to providing Canadians with accurate and timely weather information, including severe weather alerts.
• The latest forecasts and severe weather warnings are available through Environment and Climate Change Canada's weather website and the WeatherCAN app (available for Android and iOS devices).

Associated links

• Extreme Weather Event Attribution
• Public Safety Canada – Get Prepared
  
• Wildfire Smoke, Air Quality, and Your Health: Overview
• Seasonal Weather Hazards

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SOURCE Environment and Climate Change Canada