Heavy smoke from more than 100 wildfires burning in Canada, along with about four dozen large fires across 15 U.S. states, is expected to engulf large areas of the Midwest and Northeast this week, exposing millions to dangerous air pollution.

Warnings about unhealthy air extended on Wednesday, July 15, 2026, from Minnesota through Toronto and into New York. Tyler Hasenstein, a meteorologist with the National Weather Service in Chanhassen, Minnesota, advised residents to stay indoors to avoid both the smoke and the major heat, noting, “Those two things coinciding with each other is not good from a health perspective.”

In northeast Minnesota, the Boundary Waters Canoe Area Wilderness was closed Tuesday due to about 17 lightning-caused fires burning around the vast 1.1-million-acre wilderness, which is nearly the size of Delaware. Rangers estimated that between 6,000 and 10,000 people remained inside the area, according to Superior National Forest spokesperson Joy VanDrie.

Dan Westervelt, associate professor at Columbia University’s Climate School, attributed the severity of the fires to a combination of severe drought and heat in Canada and the U.S., describing it as “a perfect storm for really dry conditions to provide a lot of fuel for these wildfires to burn.” He added that research shows warming temperatures from burning coal, oil, and gas are making fires more frequent and intense.

According to the National Interagency Fire Center, fires are burning across 15 states including Minnesota, North Carolina, Colorado, Utah, Idaho, Oregon, and California. These fires have consumed over 5,678 square miles (9,138 square kilometers), an area larger than Yellowstone and Grand Canyon national parks combined.

Residents in affected regions are urged to take precautions to protect their health amid the ongoing wildfire season.

Sources