A National Weather Service meteorologist said even if winds from the northwest clear skies as expected later this week, the smoky air could keep returning until the fires are out. That could take weeks or longer.

Over 800 wildfires are burning through forests in Canada, prompting heavy smoke warnings for millions of Americans.

Wildfires in Canada are pouring thick clouds of smoke into the US and will usher in unhealthy air quality for millions of people in Northeast and Midwest.

States warned residents about air quality issues that could last for days

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