The entire state will be under an Extreme Cold Warning starting at midnight as wind chills are expected to plummet to between -20 and -45 degrees overnight.

Dangerously cold air that has settled across the Upper Midwest this week has prompted some school districts in Minnesota — including Minneapolis and St. Paul — to cancel classes on Tuesday, Feb. 18.

With extreme cold continuing on Tuesday, hundreds of schools in Minnesota and Wisconsin have announced closures and delays.