Climate change-driven heat fuels dangerous wildfires in Canada

Wildfires in Canada — forcing mass evacuations in Manitoba and prompting urgent calls for assistance from First Nations leaders in Saskatchewan — have intensified as heat, drought, and atmospheric conditions collide, during the last week of May 2025. 

Climate change is fueling this early-season heat, making high temperatures in parts of central Canada at least five times more likely than they would be in a world without climate change.

Note: This event may continue beyond May 30. Use the Global Climate Shift Index map to stay updated on heat in your region.

How unusual is the forecasted heat?

• Exceptionally warm temperatures in parts of Saskatchewan, where wildfires are actively burning, have climbed 6.6°C to 11.4°C (11.8°F to 20.4°F) above average, reaching highs up to 33°C (91°F) — well beyond the seasonal norms for late May. 

• In Manitoba, temperatures have exceeded the average by as much as 12.2°C to 13.5°C (22°F to 24.3°F), with highs also up to 33°C (91°F).

• This intense heat is tied to an unusually strong, stationary high-pressure system centered over central Canada. 

  • The system is part of a weather pattern called an “Omega Block” — a pattern locked in place by low-pressure systems over Alaska and the Upper Midwest.

• Saskatchewan and Manitoba, where wildfires are burning, are currently experiencing drought conditions ranging from “Abnormally Dry” to “Moderate Drought,” further contributing to fire risk and intensity.

• Wildfire smoke is already degrading air quality in Saskatchewan, Manitoba, and Ontario. It is expected to drift into the Midwestern United States through the weekend, where smoke could impact respiratory health in Minnesota, Wisconsin, Illinois, and Michigan.

  • Forecast Air Quality Index levels range from “Moderate” to “Unhealthy for Sensitive Groups,” with cities like Milwaukee, Detroit, and Chicago likely to see reduced visibility in the afternoon and evening.  

How has climate change influenced the heat and wildfires?

• Climate change is causing more frequent fire weather. Warming temperatures and increasingly dry air, vegetation, and soils make it easier for fires to spread, and harder to fight or prevent.

• Daily average temperatures reached Climate Shift Index (CSI) levels of 5 in central Canada from May 26 to May 29, 2025. 

  • A CSI level 5 indicates that human-caused climate change made this heat at least five times more likely, signifying an exceptional climate change event. 

• During this time, nearly 1.1 million square kilometers of land were impacted by CSI level 3, meaning average temperature conditions over that land were made three times more likely by climate change.

  • More than 320,000 square kilometers of land were impacted by CSI level 5 during this time.

• Over the entire period, just over 1 million people in Saskatchewan, Manitoba, Alberta, and Ontario experienced at least one day with CSI level 3.

What do experts say?

Dr. Kristina Dahl, VP of Science at Climate Central, said: 

"When temperatures reach a CSI level 5 across such a large area, it’s not just unusual—it means this kind of heat would be incredibly unlikely without climate change," said Dr. Kristina Dahl, VP of Science at Climate Central. "These conditions, which set the stage for dangerous wildfires, will only become more frequent and more severe if we continue burning fossil fuels."

Kaitlyn Trudeau, senior research associate for climate science and wildfire expert at Climate Central, said:
"Climate change-driven heat dries out vegetation and sets the stage for wildfires. Combine that with persistent drought and a locked-in high-pressure system, and you have a perfect storm—one that’s becoming more common as we continue to burn fossil fuels and heat the planet."

To request an interview with a Climate Central scientist, please contact Abbie Veitch at aveitch@climatecentral.org. 

How do we know climate change is influencing this heat?

The Climate Shift Index uses peer-reviewed methodology and real-time data to estimate how climate change has increased the likelihood of a particular daily temperature.

Reporting resources

• Climate Central’s More Frequent Fire Weather analysis

• Climate Central’s Extreme Weather Toolkit: Extreme Heat