The Midwest is being hit with the brunt of the cold, with temperatures plunging to 40 below zero -- the coldest in the nation -- in Brimson, Minn., as of Monday morning, according to the National Weather Service.
Alternatively, the temperature in Solana, Fla., was 81 degrees Monday afternoon
Back in the Midwest, the forecast is extreme: Wind chills were expected to drop as low as negative 55 Monday night in International Falls, Minn., and rebound to minus 25 to minus 35 on Tuesday. Farther south, the wind chill -- what it feels like outside when high winds are factored into the temperature -- is expected to hit negative 50 in Chicago and minus 35 in Detroit.
"It's just a dangerous cold," National Weather Service meteorologist Butch Dye, based in Missouri, told the Associated Press.
JetBlue Airways has stopped all scheduled flights to and from New York and Boston, and Southwest has ground to a halt in Chicago as airlines deal with a blast of freezing temperatures that has caused massive cancelations and delays.
JetBlue plans to resume some flights in the Northeast on Tuesday morning and return to full operation at four affected airports by mid-afternoon. It says the time-out would let crews rest and give mechanics a chance to service planes.
Southwest Airlines Co. suspended flights at Chicago's Midway Airport around midday and canceled more than 100 of its planned 230 daily departures there. Spokesman Brad Hawkins says Southwest hopes to reopen at Midway by Monday evening.
Nearly 3,200 flights -- one out of every 10 domestic departures -- were canceled Monday morning, following a weekend of travel disruption across the U.S. Airline officials said de-icing fluid was freezing, fuel was pumping sluggishly, and ramp workers were having difficulty loading and unloading luggage.
Some passengers have been stuck at Logan for two days, sleeping on cots and in concourse chairs.
In Mendota, Ill., about 80 miles west of Chicago, three Amtrak trains with more than 500 passengers headed for Chicago were stopped because of blowing and drifting snow.
The rail service's spokesman said passengers will remain on the trains and are being fed and kept comfortable by the crew. Railroad employees were working late Monday to reopen the tracks to get the trains moving.
The Northeast will be hit with cold on Tuesday, according to The Weather Channel, with single-digit highs expected in most parts of the region while temperatures will be in the teens in Boston, New York City and Philadelphia. Tuesday's high of 14 degrees in New York City will be more than 40 degrees less than Monday' high of 55 degrees.
For most of the Midwest, the cold weather followed close behind a system that had brought a foot of snow and high winds that made traveling risky.
Roads were treacherous across the region. 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 a blizzard in 1978.
"I know the roads look clear, the sun's out and it all looks nice," Ballard said Monday. "But it's still minus 40 in wind chill -- deadly temperatures. So we want to be very, very careful."
National Weather Service meteorologist Philip Schumacher urged motorists in the Dakotas -- where wind chills were as low as the minus 50s -- to carry winter survival kits and a charged cellphone in case they become stranded.
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.
The National Weather Service said the snowfall at Chicago's O'Hare International Airport totaled more than 11 inches -- the most since the Feb. 2, 2011, storm that shut down the city's famed Lake Shore Drive.
Elnur Toktombetov, a Chicago taxi driver, woke up at 2:30 a.m. Monday anticipating a busy day. By 3:25 a.m. he was on the road, armed with hot tea and doughnuts. An hour into his shift, his Toyota's windows were still coated with ice on the inside.
"People are really not comfortable with this weather," Toktombetov said. "They're really happy to catch the cab. And I notice they really tip well."
In downtown Chicago, a commuter train hit a "bumping post" as it pulled into a station, the second such accident of the day. Metra spokesman Michael Gillis said six passengers were taken to a hospital with minor injuries Monday after the train hit the post at the end of a platform. A less serious incident occurred at the same station around 6:15 a.m., but no passengers were injured.
Continuing a decades-old practice, Chicago Transit Authority was handing out fare cards to social service agencies to be distributed to the homeless so they could ride buses and trains to stay out of the cold.
Missouri transportation officials said it was too cold for rock salt to be effective, and several Illinois roadways were closed because of drifting snow.
Late Sunday night, a bus carrying Southern Illinois University's men's basketball team back from a game against Illinois State got stuck in the snow at the side of Interstate 57. Assistant coach Anthony Beane Sr. told The Southern Illinoisan no one was injured and the plan was for the team to spend the night at a hotel in nearby Tuscola. Beane and the players had to wait for a tow truck to get the bus out of the snow. Beane told the newspaper that if a truck was unable to reach the bus, the Illinois State Police had agreed to help the team get to its hotel.
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.
School was called off Monday for the entire state of Minnesota, as well as cities and districts in Wisconsin, Illinois, Indiana, Ohio and Iowa, among others. Chicago Public School officials reversed an earlier decision to keep schools open, announcing late in the day Sunday that classes would be canceled Monday.
Government offices and courts in several states closed Monday. In Indiana, the General Assembly postponed the opening day of its 2014 session, and the state appellate courts, including the Indiana Supreme Court, said they would be closed.
More than 40,000 homes and businesses in Indiana, 16,000 in Illinois and 2,000 in Missouri were without power early Monday.
Southern states were bracing for possible record temperatures, too, with single-digit highs expected Tuesday in Georgia and Alabama.
Temperatures plunged into the 20s early Monday in north Georgia, the frigid start of dangerously cold temperatures for the first part of the week. The Georgia Department of Transportation said its crews were prepared to respond to reports of black ice in north Georgia.
Temperatures were also expected to dip into the 30s in parts of Florida on Tuesday. Though Florida Citrus Mutual spokesman Andrew Meadows said it must be at 28 degrees or lower four hours straight for fruit to freeze badly, fruits and vegetables were a concern in other parts of the South.
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.
"We are hoping this isn't going to be more than a few days of cold weather, but we did learn with the ice storm that you can wake up in the 19th century and you need to be able to not only survive, but be comfortable and continue with your basic day-to-day functions," Nickell said.