CHICAGO — Snow-covered roads, high winds and ice were creating dangerous driving conditions Sunday from the Dakotas to Missouri to Delaware ahead of a ‘‘polar vortex’’ that’ll bring below-zero — and possibly record-breaking — temperatures not seen in years to much of the nation.
The counterclockwise-rotating pool of cold, dense air will affect more than half of the continental US throughout Sunday and into Monday and Tuesday, with wind chill warnings stretching from Montana to Alabama. With it comes a startling forecast: 25 below zero in Fargo, N.D., minus 31 in International Falls, Minn., and 15 below in Indianapolis and Chicago.
‘‘It’s just a dangerous cold,’’ National Weather Service meteorologist Butch Dye in Missouri said.
Several states in the Midwest were getting walloped with up to a foot of new snow, and residents shoveled out and stocked up on groceries before bitterly cold temperatures set in overnight.
Five to 7 inches fell overnight in the Chicago area, while 8 to 10 inches was expected to fall in central Illinois, Indiana and Michigan later Sunday, National Weather Service meteorologist Ed Fenelon said. Forecasts also called for several inches in western Tennessee and 1 to 3 inches in Kentucky.
In Chicago, temperatures were expected to fall throughout Sunday to about 11 degrees by 5 p.m., ‘‘and from there it will be a freefall for the rest of the night,’’ with temperatures bottoming out around minus 15, likely setting a daily record, Fenelon said. Earlier Sunday, the National Weather Service reported temperatures in the 20-below range in northern Minnesota and Grand Forks, N.D.
It hasn’t been this cold for almost two decades in many parts of the country. Because of that, medical experts are reminding people that frostbite and hypothermia can set in quickly at 15 to 30 below zero, and say it’s key to dress in layers, hats and gloves.
In St. Louis, grocery stores sold out of the essentials before Sunday’s weather onslaught.
‘‘The problem is the bread is sold out. We’re out of milk. We sold out of chips, chicken wings, some meats,’’ Issa Arar of Salama Supermarket said.
Michigan residents had also jammed stores to stock up on supplies.
‘‘I made my husband go grocery shopping last night,’’ said Kim Tarnopol, 46, of the Detroit suburb of Huntington Woods. Tarnopol was picking up cold medicine Sunday for her daughter Emma at a CVS in nearby Berkley, Mich.
Travel problems started early Sunday. In New York City, a plane from Toronto landed at Kennedy International Airport and then slid into snow on a taxiway. No one was hurt, though the airport temporarily suspended operations because of icy runways.
About 1,200 flights had been cancelled Sunday at O’Hare and Midway international airports in Chicago, aviation officials said, and there also were cancellations Logan International Airport in Boston and Tennessee’s Memphis and Nashville international airports.
Roads in the Midwest were particularly dangerous. Indiana State Police said Interstate 70 in the western part of the state was snow-covered, while officials in Missouri warned it was too cold for rock salt to be very effective.
‘‘If it gets to the point where it’s no longer safe, we will consider suspending operations,’’ Missouri Department of Transportation spokeswoman Marie Elliott said.
School has been called off Monday for the entire state of Minnesota, as well as cities and districts in Wisconsin, Illinois and Indiana, among others.
Southern states are bracing for possible record temperatures, too, with single-digit highs expected Tuesday in Georgia and Alabama.
In western Kentucky, Smithland farmer David Nickell moved extra hay to the field and his animals out of the wind. The instructor at West Kentucky Community and Technical College had 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.
‘‘Personally, I thought the ice storm should become an annual event ... It definitely taught people to be prepared and appreciate normalcy.’’
At a New Orleans-area nursery that sells 25 varieties of citrus and fig trees, a man who answered the phone didn’t have time to talk or return a call asking about his surname. The Saxon Becnel & Sons website said the nursery has 1 million trees at its two locations.
The cold wasn’t as threatening at Stella Plantation, although manager Hugh French had hoped to harvest navel oranges through January.
‘‘We pick our A-1 fruit first,’’ he said. ‘‘So some of what’s left on the tree would be culls — not the prettiest looking fruit, but it still tastes good.’’
The season for satsumas, a sweet mandarin orange and a mainstay of Louisiana’s citrus crop, was already over. And the plantation only has a few grapefruit trees.
‘‘We’re toward the end of the season now. If we lose it it’s not going to be that detrimental,’’ he said.
Sunday’s NFL playoff game in Green Bay’s Lambeau Field could be among one of the coldest ever played: A frigid minus 2 degrees when the Packers and San Francisco 49ers kick off around 3:30 p.m. CST. Doctors suggest fans wear at least three layers and drink warm fluids — not alcohol.
Associated Press reporters Jim Salter in St. Louis; Brett Barrouquere in Louisville, Ky.; Verena Dobnik in New York City; David N. Goodman in Berkeley, Mich.; and Janet McConnaughey in New Orleans contributed to this report.