Wondering why it smells like smoke outside? Canadian wildfires are impacting millions in Ontario, Minnesota, Toronto, New York, Michigan, Wisconsin and Boston.

Wildfire smoke has settled thickly in parts of New York, Connecticut, Wisconsin, Michigan and Minnesota—and it’s heading further south.

A massive plume of smoke from wildfires burning across Canada has swept into the United States, degrading air quality across the Midwest, Northeast and Mid-Atlantic.