Record-shattering arctic cold has reached as far south as Florida, with freeze warnings in place from Texas to the Atlantic Coast and the northeastern United States facing another cold wave at the end of the week.
Temperatures were from 11 to 17 degrees Celsius below normal across the United States east of the Rocky Mountains, with only southern Florida untouched by the arctic blast, forecasters said on Monday.
"That degree of cold will be with us until tomorrow," said Brian Hurley, a National Weather Service meteorologist at College Park, Maryland.
"Tuesday morning, we're looking at temperatures with very high probability of record lows."
Along Alabama's Gulf Coast, the temperature in the city of Mobile could hit a low of minus 9C overnight.
Stiff breezes are expected to create dangerously cold wind chills across southeastern Georgia and most of northeastern Florida, the weather service said.
The mass of frigid air pumped south by a dip in the jet stream sent temperatures plunging across the US heartland.
Omaha posted a low of minus 29C, breaking a 130-year-old record, and Aberdeen, South Dakota, shattered a record set in 1919 with a temperature of minus 36C.
The cold will be unrelenting across the Middle Atlantic and northeastern United States, with up to two dozen low temperature records expected in those regions over the next day or two, Hurley said.
Although the cold should ease across most of the United States after Tuesday, the northeastern quarter of the country will see a repeat of the current frigid temperatures from Thursday to Friday as another arctic blast hits the area.
The only part of the United States spared the deep freeze is the southwest, with above-normal temperatures and dry weather expected to continue there, the weather service said.