Over 830 wildfires burn across Canada, with many classified as out of control. Thick smoke blankets parts of Canada and the United States, affecting air quality. Officials warn of unhealthy air levels in several major cities through the week. Minnesota's Boundary Waters Canoe Area Wilderness faces evacuations due to lightning-caused fires. Experts cite drought and heat as reasons for the widespread and intense wildfire season.

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.