MINNEAPOLIS – Unhealthy air has invaded Minnesota, Wisconsin, Michigan and North Dakota early this week as a new round of wildfire smoke from Canada has wafted into the region, choking areas as far south as Chicago and Detroit. 

The FOX Forecast Center is tracking heavy ground-level smoke from Canadian wildfires moving into the U.S. early this week, delivered by northerly winds behind a cold front. 

On Monday morning, some of the worst air quality in the U.S. was reported over the Upper Midwest and Great Lakes regions, for cities including Duluth, Minnesota, and Marquette, Green Bay and Milwaukee in Wisconsin. 

Based on the Air Quality Index, some of these areas could see unhealthy air quality throughout Monday. 

An Air Quality Advisory is in place for all of Wisconsin on Monday, according to the Wisconsin Department of Natural Resources. 

THE AIR QUALITY INDEX EXPLAINED: WHAT AIR QUALITY IS BAD?

The Minnesota Pollution Control Agency issued an Air Quality Alert for northeast Minnesota through Monday evening. Smoke suffocated most of the state through the weekend, but improved in southern Minnesota on Monday. However, another round of wildfire smoke moved into northwest Minnesota, causing poor air quality.

An Air Quality Alert is in effect statewide in Michigan throughout Monday as a new plume of smoke moves in. 

Under unhealthy air quality conditions, young children and older adults, along with individuals with lung and heart conditions, including asthma, should avoid prolonged time outdoors and heavy exertion.

The public is advised to reduce activities that could contribute to air pollution, such as outdoor fires and vehicle idling.

Wisconsin and Minnesota are seeing the worst air quality Monday, with unhealthy air also reported across parts of Michigan.

The FOX Forecast Center said air quality should improve by midweek as the smoke moves out.

Earlier this summer, wildfire smoke descended from Canada into the Northeast and mid-Atlantic, creating brightly hued sky and reducing the air quality for New York and Washington, D.C.

U.S. AIR QUALITY MAP

This is not the last of the wildfire smoke. Canadian fire crews continue to battle more than 400 large active fires and more than 13 million acres have burned this year. 

So far, 2025 has not been as devastating as the 2023 Canada wildfire season, which was historic for the amount of acres burned, people impacted and the health impacts across North America, according to the Canadian Department of Natural Resources. 

On average, Canada sees about 8,000 wildland fires, burning 2.1 million hectares (5.2 million acres). In 2023, more than 15 million hectares (37 million acres) of Canada’s forests burned.