• Dense smoke from more than 100 active wildfires in Canada and Minnesota has enveloped large areas of the north-central and northeastern United States, triggering air quality alerts from Minnesota to New York and Maine.
  • The Boundary Waters Canoe Area Wilderness in northeastern Minnesota was closed after multiple lightning-caused fires broke out, and officials said thousands of people were being evacuated from the remote area.
  • The Canadian Air Force rescued two groups of young campers who had crossed the border into Canada, Minnesota Gov. Tim Walz said Wednesday.
  • Health officials warned that high levels of fine particulate matter in wildfire smoke can harm children and people with heart or lung conditions.

Boundary Waters wilderness closed as fires burn across Canada and Minnesota

Thick smoke from more than 100 active wildfires burning in Canada and Minnesota swept across the north-central and northeastern United States this week, exposing millions of people to dangerous air pollution as air quality alerts stretched from Minnesota through Toronto to New York and Maine, according to the National Weather Service.

The smoke, carried southeast by prevailing winds, combined with unusually high summer temperatures. In northeastern Minnesota, multiple lightning-caused fires were burning around the Boundary Waters Canoe Area Wilderness, a remote area primarily accessible by canoe. The wilderness area was closed Tuesday, and officials said thousands of people were being evacuated, according to the Associated Press.

The Canadian Air Force rescued two groups of young campers who had crossed the border into Canada, Minnesota Gov. Tim Walz said Wednesday. He said they appeared to be safe.

High levels of fine particulate matter in wildfire smoke can harm sensitive groups including children and people with heart or lung conditions, according to health officials. The particles can cause shortness of breath, coughing, dizziness or fatigue, and can aggravate heart and lung diseases as well as other chronic health problems.

The 2026 fire season has been particularly intense in the United States. About four dozen large fires were burning in 15 states from Minnesota and North Carolina to Colorado, Utah, Idaho, Oregon and California, according to the National Interagency Fire Center.

Prolonged drought and record-low snowpack combined to create conditions conducive to rapid fire growth, officials said.

Officials in Michigan and Wisconsin warned residents about air quality problems that could last days, and the effects extended into Maine, where residents reported a yellowish and brownish tint to the sky. The dense smoke could reach as far as Washington, D.C., by midday Thursday, according to the National Weather Service.