A new report says the conditions that fuelled July wildfires in Ontario and the Northwest Territories were made roughly twice as likely due to human-induced climate change.
The report by an international team of scientists says what were once rare fire conditions are now increasingly likely today due to climate change, driven by the burning of fossil fuels.
The World Weather Attribution report says early observations indicate the hot, dry and windy conditions underlying fires in the Northwest Territories could now be expected to occur every two to six years, and every six to 15 years in Ontario.
In a world without human-caused climate change, the report suggests those conditions would have been much rarer, or less than once in 40 years.
Early estimates suggest this is the worst wildfire season on record in Ontario and in the Northwest Territories’ top 10.
The vast majority of Ontario’s wildfires burned during a few intense days in July, on the back of a scorching heat wave and intense lightning activity along a roughly 500-kilometre storm front over the province’s northern boreal forest.
Thousands of evacuees from more than a dozen predominantly First Nations communities fled their homes while noxious plumes of smoke deteriorated air quality for millions of people from Thunder Bay to the northeastern United States.
Extreme fire weather has been more sustained in the Northwest Territories, where fires have remained active and spread over a long period rather than being driven by a single week of explosive growth.
To come up with the results, scientists used observations and climate models focusing on the seven-day and 30-day periods of most extreme fire weather in Ontario and the Northwest Territories, and compared those conditions against what would have been expected in a world without fossil fuel emissions.
This report by The Canadian Press was first published Aug. 6, 2026.
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