How it works: The map above is built with data from the nonprofit climate research group Climate Central and is based on the average date of the first fall freeze between 1991 and 2020.

Detroit's first freeze is expected around Oct. 23. The big picture: The map above shows the average date of the first freeze — defined as the first day temperatures drop to 32°F or below ...

The Frost and Freeze map shows where frost cant be expected and where temperature are forecast to fall below 32 degrees F. Frost is a solid deposition of water vapor from saturated air.

National Weather Service meteorologists warned of temperatures cold enough to be fatal descending across most of the nation.