Climate extremes fuel explosive wildfires in Canada and western U.S.

The United States is burning faster than usual this year, while massive smoke plumes from Canadian wildfires deplete air quality on both sides of the border. Experts believe the severity of the current fire season, affecting millions of acres of land between both countries, was primed by climate extremes.

More than 100 wildfires raged in Canada on Thursday and strong winds were carrying their smoke — plus more from a few large fires in Minnesota — across the Upper Midwest and northeastern U.S., exposing millions to harmful pollution.

Around 3,500 Canadian fires have enveloped about 2.3 million acres of land this year, a startling statistic that's more or less on par with the country'a 10-year average number of acres burned by mid-July. It's actually lower than Canada's 5-year average, which is twice as high after recent extreme fire seasons.

Fire seasons, in Canada, the U.S. and elsewhere across the world, are starting earlier and lasting longer. They're also "harder to contain," smoldering through the winter as "zombie fires," according to the Canadian Climate Institute, which has noted how climate change worsens wildfire threats and, in some instances, may multiply "the likelihood of extreme fire weather" several times over.

In the U.S., close to 40,000 fires have torn through more than 3.6 million acres so far in 2026, including half a million acres in the last two weeks alone, according to the U.S. National Interagency Fire Center. That's almost 10,000 more fires, and almost a million more acres burned, than the 10-year average for mid-July. In a new advisory, the center said "fire activity is already mirroring conditions normally not seen until later in the season."

Blazes have scorched hundreds of thousands of acres since January in the American West, with Colorado and Utah hit hardest. At the end of June, three firefighters died and two were injured in the Knowles Fire along the states' shared border.

Of the 48 large wildfires still active nationwide, 10 are in Colorado or Utah. Most others are scattered across Arizona, California, Idaho, Nevada, New Mexico, Oregon and Washington state.

"From a landscape point of view, from a fuels point of view, and from a weather and climate point of view, everything has kind of converged," Jon Meyer, Utah's assistant state climatologist, told CBS News.

Prolonged drought, record heat and historically low snowpack in western states have created "the perfect storm of conditions," as Meyer put it, for one of the region's worst wildfire seasons in a decade.

Nick Nausler, of the National Weather Service's St