Early-morning freeze warnings are covering much of the same areas in Alabama that a series of tornadoes ravaged over the weekend.
An arctic blast moved across the eastern two-thirds of the United States nearly two weeks before the start of spring.
Around 80% of the country was below freezing Tuesday morning, with a chill felt as far south as Houston, Mobile, Alabama, and Atlanta, CNN meteorologist Dave Hennen said.
The freeze warnings stretch from Texas to the Carolinas, covering more than 55 million in the Deep South.
The bitter cold could mean new worries for those in Lee County, Alabama, where 23 people died after tornadoes tore through the region Sunday.
Residents have been displaced after the twisters destroyed their homes, and searchers are still picking through the debris for potential victims. The area will see temperatures in the mid-20s Tuesday and Wednesday mornings.
Record-setting lows possible across the US
Wind chill advisories are in effect for parts of the Rockies, the Plains, the Great Lakes region and Appalachians, Hennen said. Temperatures will be as much as 30 degrees Fahrenheit below normal over much of the eastern two-thirds of the country, he said
Dozens of records could be broken Tuesday, with some 14 record lows possible in Texas, CNN meteorologist Taylor Ward said.
Records also were expected to be broken in cities in Kansas, Kentucky and Pennsylvania, Ward said.