Canada wildfires worsen air quality across Midwest, Northeast US

Brian K. Sullivan, Bloomberg News on Aug 3, 2025

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Smoke and grit from hundreds of forest fires have spread across large parts of Canada and the northern U.S., sending air quality across the Midwest and northeast U.S. and Toronto to unhealthy levels.

Air quality deteriorated to moderate in Chicago early Sunday with some areas unhealthy for sensitive groups, and to unhealthy in Milwaukee and downtown Toronto, Canada’s largest city, according to AirNow.gov. Alerts were raised across Canada from the Northwest Territories to Quebec, as well as in 10 U.S. states from Minnesota to Maine, including Upstate and western New York.

With weather patterns expected to hold steady, there is little chance of immediate relief, forecasters noted.

“The overall flow is still out of the west; it doesn’t look like it is going to change much overall,” said Bob Oravec, a senior branch forecaster with the US Weather Prediction Center. “It goes out through the week.”

More than 730 forest fires are raging across Canada with at least 210 out of control, according to the Canadian Interagency Forest Fire Centre. The smoke from the blazes, which have consumed 6.6 million hectares (16.3 million acres), have often drifted south in the U.S. at various times this spring and summer, including casting a pall over the Lollapalooza music festival in Chicago on Friday.

In recent years, the massive smoke clouds drifting from Canadian fires have triggered a series of emergencies across the eastern U.S., and at one point turned Manhattan’s skies an apocalyptic orange. The smoke has crossed the Atlantic at times, clouding European skies and dropping soot across the Arctic. Scientists are looking into whether the smoke is contributing to melting ice there and rising temperatures.

Steady wind out of the northwest will keep the smoke drifting into the U.S. for at least the coming week, Oravec said. The conditions that broke the hot, humid weather across the eastern U.S. are also partially to blame for the spreading smoke, he said. Temperatures in New York’s Central Park, for instance, dropped from the mid to high 90sF last week to just 80F Saturday, the National Weather Service said.

Oravec said until the fires are extinguished, there will likely be continued rounds of smoke and ash drifting south.

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