Nearly 187 million people, more than half of the nation's population, were under a wind chill warning or advisory on Monday.
The coldest temperature reported in a 24-hour period through Monday was -36 degrees at Crane Lake, Minnesota, while the warmest was 84 at Hollywood and Punta Gorda, Florida.
Record low temperatures have already been set; at Chicago's O'Hare International Airport, temperatures of minus 16 degrees were recorded at 8am on Monday, beating the previous record of minus 14 set in 1988.
With wind chill warnings stretching from Montana to Alabama, much of the U.S. is experiencing the coldest temperatures in almost 20 years, according to the National Weather Service. They are expected to be 30 to 50 degrees below average in some cities - and the deep freeze is expected to last into Tuesday.
The winds made it feel like 55 below zero in International Falls, Minn., and parts of the Midwest accustomed to temperatures that are cold - albeit seldom this cold. But even the coal fields of Virginia and West Virginia, the wind chill was negative 35.
The coldest temperature reported in a 24-hour period through Monday was -36 degrees at Crane Lake, Minn. The warmest: 84 at Hollywood and Punta Gorda, Fla.
The deep freeze is to blame for an estimated 13 deaths so far - almost all of them from traffic accidents. A man in Wisconsin died of hypothermia, while an elderly woman with Alzheimer's disease was found dead in the snow about 100 yards away from her home in New York state after wandering out.
New York Gov. Andrew Cuomo has declared a state emergency covering 13 counties into western New York, while parts of the state Thruway in western New York are be closed from 8 p.m. on Monday.
'To ensure an effective and rapid response to this winter storm, I am declaring a state of emergency, so resources can get to communities where they are needed as quickly as possible.'
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.
Meteorologists have warned about the weather 'dangerous, life-threatening winds', that could inflict frostbite on exposed skin in just 10 minutes.
'Skin freezes in just five minutes with a wind chill of minus 50,' said HLN meteorologist Bob Van Dillen as wind chills are putting temperatures in northern Minnesota at 60 below zero.
Delays at O'Hare were average about 40 minutes, while reported delays are about 20 minutes at Midway.
Operations will begin to ramp up again at 10 a.m. Tuesday and the airline expects to be fully operational by 3 p.m. Tuesday. It will allow the company to rest crew and give it time to service aircraft.
‘It's just a dangerous cold,’ said National Weather Service meteorologist Butch Dye in Missouri.
It hasn't been this cold for almost two decades in many parts of the country. Frostbite and hypothermia can set in quickly at 15 to 30 below zero.
A Chicago native, she said thermal underwear, lots of layers and ‘Eskimo coats’ with zipped hoods to block the wind were the norm growing up. ‘And don't go out if you don't have to,’ she said.
In the parking lot, Craig and Renee Heling of Waukesha, Wisconsin, set up a camouflage hunting blind behind his white pickup truck and tailgated next to a propane heater. He wore four layers of clothing up top, two on his legs: ‘Two wool socks on - right now, I feel comfortable,’ he said.
Indianapolis Mayor Greg Ballard upgraded the city's travel emergency level to ‘red,’ making it illegal for anyone to drive except for emergencies or seeking shelter. The last time the city issued such a travel warning was during the 1978 blizzard.
Missouri transportation officials said it was too cold for rock salt to be very effective, and several Illinois roadways were closed because of drifting snow.
A bus taking the Southern Illinois University men's basketball team home from a game at Illinois State got stuck in the snow Sunday night off Interstate 57, forcing the group to wait for a tow truck and make plans for a night at a hotel in nearby Tuscola, Illinois.
Many cities came to a virtual standstill. In St. Louis, where more than 10 inches of snow fell, the Gateway Arch, St. Louis Art Museum and St. Louis Zoo were part of the seemingly endless list of things closed. Shopping malls and movie theaters closed, too. Even Hidden Valley Ski Resort, the region's only ski area, shut down.
Chicago Public School officials reversed an earlier decision to keep schools open, announcing late in the day on Sunday that classes would be canceled on Monday.
Ray Radlich was among the volunteers at New Life Evangelistic Center, a St. Louis homeless shelter, who was braving the cold as part of search teams that seek out the homeless and get them to shelters.
'I get all achy and pained all the way up my feet, to my legs, up my spine,' Salvaje said.
Southern states are bracing for possible record temperatures, too, with single-digit highs expected Tuesday in Georgia and Alabama.
With two freezing nights ahead, Louisiana citrus farmers could lose any fruit they cannot pick in time.
In Plaquemines Parish, south of New Orleans, Ben Becnel Jr. estimated that Ben & Ben Becnel Inc. had about 5,000 bushels of fruit on the trees, mostly navel oranges and the sweet, thin-skinned mandarin oranges called satsumas.
In western Kentucky, Smithland farmer David Nickell moved extra hay to the field and his animals out of the wind. He'd also stocked up on batteries and gas and loaded up the pantry and freezer. The 2009 ice storm that paralyzed the state and knocked out power to hundreds of thousands of people is fresh in his mind.