On Monday morning, Nashville was 40 degrees colder than Albany, New York. Memphis, Tennessee, was 20 degrees colder than Anchorage, Alaska. And Atlanta was colder than Moscow -- either Russia or Idaho.
But the U.S. South was downright balmy compared to the Great Lakes region, where temperatures hovered in the negative 20s -- before wind chill, which dropped temps to the negative 50s, making it very dangerous to go outside.
In Minneapolis, where it was 12 below zero on Monday afternoon, blowing snow shrouded bridges over the frozen Mississippi River. In Fairfield, Iowa, at nine below, CNN iReporter Deborah Roberts called Monday "a good day to stay in and use the excuse it's too darn cold."
The bitter cold that a "polar vortex" is pushing into much of the United States is not just another winter storm. It's the coldest in 20 years in many areas, breaking records in places like Chicago, where it was minus 16 overnight and minus 14 at noon.
"I ask everyone to keep exercising good judgment and remain indoors if at all possible, to take the warnings and advisories seriously, and to check on the well-being of family, friends, and neighbors," Chicago Mayor Rahm Emanuel said Monday in a written statement. Illinois Gov. Pat Quinn, meanwhile, called on state residents to stay off the roads and activated National Guard troops to help local authorities clear highways.
More than 30 states had posted some sort of wind chill warning or advisory on Monday. Morning wind chills were nearly 60 below in parts of northern Minnesota. At minus 50, skin can freeze in less than five minutes, HLN meteorologist Bob Van Dillen said.
Authorities have blamed the deep freeze for 13 deaths so far, nearly all of them from traffic accidents. But a man in Wisconsin died of hypothermia, and an elderly woman with Alzheimer's disease who wandered away from her home in New York state was found dead in the snow in a wooded area about 100 yards away.
The deep freeze has also snarled air traffic across the country, with more than 3,500 flights canceled by noon ET, according to flightaware.com. Among those stuck waiting for a way home was New York resident Mindy Goldberg, whose family's flight back from Mexico had been diverted to Boston because of bad weather.
"I just called my kids' school to tell them they wouldn't be there, and she said, 'Everyone's stuck somewhere,' " Goldberg told CNN affilliate WBZ.
In Indianapolis, Los Angeles resident and iReporter Jason Bentley took some time out to play in the snow outside the airport after learning his flight home had been canceled Sunday. It was 15 below zero.
"This is the wettest snow I've ever touched," Bentley said. "The easiest snow to make a snowman and to have snowball fights. It's also probably the worst (weather) I've ever been in because of the temperature."
And the Northeast will be seeing its own brutal drop in temperatures as the arctic air works its way east. In New York, where it was about 50 degrees with wind chill Monday morning, could go as low as minus 7 on Tuesday, said CNN meteorologist Indra Petersons -- a nearly 60-degree temperature change in a single day.
In a very rare move, Minneapolis issued a "Particularly Dangerous Situation" warning about the "historic and life-threatening cold." Such warnings are typically issued for tornadoes, said Petersons.
The National Weather Service adopted the Twitter hashtag "#Chiberia" for Chicago. (Parts of the vast Siberian region, such as Tobolsk, had Fahrenheit temps in the low teens Monday, though other parts had temperatures of 50 below zero.)
Some of the greatest concern surrounds the tens of thousands of Midwesterners without electricity.
More than 15,000 customers in Indiana, 6,800 in Illinois and 2,200 in Missouri didn't have power overnight, according to utility companies.
Chicago opened up 12 centers for residents to seek warmth, one of which was to stay open all night through Tuesday. Libraries and some other city facilities would also be open, said Evelyn Diaz of the city's Department of Family and Support Services. Quinn said 100 warming centers were open statewide.