Canada has 858 wildfires, including 30 new fires on Thursday. Most of the fires are not under control. Many large fires are in northern Ontario. Strong winds are carrying thick smoke south into the United States.

The smoke has made the air dangerous in Michigan, Minnesota, New York, and other northern states. People in some areas should stay inside. Detroit has the worst air quality in the world now, a Swiss air group said. New York City has opened cooling centers and is giving people KN95 masks. Smoke may reach New Jersey before the World Cup final on Sunday.

Hundreds of First Nations people in northern Ontario have left their homes. Some homes and buildings have burned. More than 150 fire teams are working in Ontario. Canadian Prime Minister Mark Carney said Canada and the US must work on climate change. Rain may come soon, but it may not stop the fires. A wind change on Monday may improve the air in the US.