(CNN) -- 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.
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.
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, and breaking some records.
About 3,300 flights nationwide were canceled by noon ET Monday, according to flightaware.com.
While the current weather patterns gave the Northeast a bit of a reprieve, it's in for a brutal drop as the arctic air works its way east. New York, where it's about 50 degrees with wind chill Monday morning, could go as low as minus 7 on Tuesday, said CNN meteorologist Indra Petersons. The region could face a 60-degree temperature change in a single day.
The temperature spread within the United States is a stunning 130 degrees, CNN meteorologist Dave Hennen said, with wind chill putting northern Minnesota at 60 below zero, while Key West, Florida, basks in its dreamy 70 degrees. Much of the West can also expect relatively pleasant weather through Tuesday.
But from Minneapolis to Chicago to Milwaukee, people are under health warnings to stay indoors. Many schools have closed.
"Skin freezes in just five minutes with a wind chill of minus 50," said HLN meteorologist Bob Van Dillen.
Frostbite occurs in 10 minutes with wind chills of minus 35, Hennen added.
Over the past week, at least 13 people have died of weather-related causes. Eleven people died in road accidents; one 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.
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, where temperatures were at 14 below zero. (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.)
"The steam from my shower froze on the window," said Fahd Alvi in Chicago.
In Atlanta, Katie Fallon joked, "My shoes do not even match my outfit this morning! Had to go fuzzy socks and hiking boots for warmth."
The immediate forecast offers little relief. But by Wednesday, temperatures will start edging closer to normal, forecasters said, and by Thursday temperatures in most of the country will be back to normal, or even above normal.
"It's bitterly 10 degrees here in Weatherford, Texas, with a wind chill of below zero," said Elizabeth Brew. "Very hard to watch my kids go to school in such weather, but it is what it is."
Here's what to expect Monday:
Astonishing cold in the Midwest
High temperatures in parts of the Midwest won't even get up to zero, the National Weather Service said.
Throw in some fierce winds, and you get wind chills like 55 below zero in Duluth, Minnesota; minus 34 in Chicago; and minus 24 in St. Louis.
The extreme weather prompted school cancellations Monday in many major school districts, including St. Louis, Chicago, Detroit, Indianapolis and Milwaukee.
"It's not just a snow event, it's a cold event, and that's what scares us," Indianapolis Mayor Greg Ballard said. He urged residents to stay off the streets, especially after nightfall.
The Southern Illinois University men's basketball team, fresh off a game against Illinois State, got trapped on the side of Interstate 57 late Sunday and was prepared to spend the night on the bus, SIU Athletic Director Mario Moccia said.
There wasn't a massive amount of snow on the ground, Moccia said. Rather, it was the blowing snow that made the road virtually impossible to see.
The bus driver decided to pull off the road and get out of the way of traffic until visibility improved. But when the driver tried to get back on the road, there was no traction, and the bus was stuck.
"They're just hanging out, they're watching movies," Moccia told CNN late Sunday night. He said the bus had plenty of fuel, heat and food, and the team was waiting for a tow truck.
Players later tweeted that they were going to spend the night at a nearby church in Tuscola, Illinois.
"Somehow this eventful day/night has led to our team sleeping on the floor of a church in Tuscola. What a journey it has been," Dawson Verhines tweeted.
In Embarrass, Minnesota, residents wondered whether they might see their cold-temperature record of 64 below zero, set in 1996, snap like an icicle.
"I've got a thermometer from the weather service that goes to 100 below," resident Roland Fowler told CNN affiliate KQDS. "If it gets that cold, I don't want to be here."
Deep freeze in the Deep South
Hard freeze warnings are in effect across much of the Deep South, from eastern Texas to Florida. That includes virtually all of Louisiana until late Monday morning, the National Weather Service said.
The arctic blast threatens to sweep subzero lows as far south as Alabama and plunge much of the South into single digits.
Tennessee declared a state of emergency as it braced for the coldest temperatures since 1994 on Monday.
"Temperatures will not get above freezing until Wednesday night," the Tennessee Emergency Management Agency said. It warned of rapidly falling temperatures and slick roads from flash freezing.
As if the brutal cold isn't bad enough, tens of thousands of Midwesterners are dealing with no 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. Illinois Gov. Pat Quinn said 100 warming centers were open statewide.
This, too, shall pass
If there's any good news about the biting cold snap, it's that most of it should be over by Wednesday. That's when a warming trend should begin, the National Weather Service said.
CNN's Joe Sutton, Mari Ramos, Todd Borek, AnneClaire Stapleton and Julia Lull contributed to this report.
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