Smoke from Canadian wildfires drifted across North America this week, blanketing cities in a thick yellow haze.

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.

Residents have been warned to stay indoors to avoid both the smoke and the extreme heat