Last week, Canadian wildfire smoke blanketed Wisconsin and caused the Air Quality Index to reach the unhealthy level for sensitive groups. Six days later, on July 31, the smoke appears to have a worse impact on the air.

A blanket of smoke fills the air from Canadian wildfires moving south in downtown Milwaukee on July 31, 2025. The Wisconsin Department of Natural Resources issued an air quality advisory for all of the state. The smoke is expected to move back north on Aug. 1.

Smoke from hundreds of wildfires burning in Canada is blanketing the skies in the Midwest, leaving millions with dangerous breathing conditions.