Enjoying the 'Polar Vortex'? Stand by for more.

More cold is on the way for already-frozen portions of the United States. Combined with gusty winds, these temperatures will result in life-threatening wind chill values as low as 60 degrees below zero, reports the National Weather Service.

Except for those crazy guys with their shirts off, most football fans at Lambeau Field for the Packers-49ers game Sunday afternoon in Green Bay, Wisconsin, were bundled up to the eyebrows, some of them gathered around parking lot fires set to warm their tailgate parties.

How come? Let the National Weather Service explain:

“The coldest temperatures in almost two decades will spread into the northern and central US today behind an arctic cold front. Combined with gusty winds, these temperatures will result in life-threatening wind chill values as low as 60 degrees below zero. Also, heavy snow will develop from the eastern Plains to the Great Lakes today, with up to a foot of accumulation possible.”

As the Weather Channel continues the narrative reminiscent of scenes of the Russian steppes from “Dr. Zhivago” …..

“Morning lows Monday will be in the 20s and 30s below zero over much of eastern Montana, North Dakota, northeast South Dakota, Minnesota, northwest Illinois, and Wisconsin. Relentless northwest winds of 15 to 35 mph (depending on location) will make this an exceptionally dangerous cold, sending wind chills into the minus 50s and even minus 60s across much of this region. At these levels, any exposed skin can suffer frostbite in as little as 5 minutes!

“Subzero cold will plunge as far south as the Ozarks and Ohio Valley, including Cincinnati, Ohio and Springfield, Mo. Daily record lows are possible in at least two dozen major cities from Texas to the Midwest including Minneapolis/St. Paul, Kansas City, and Austin, Texas.”

For those of you who thrill to news about windchill and the dangers of frostbite and hypothermia, go here.

Meanwhile, about 2,855 flights had been delayed nationwide by midday Sunday and 2,332 had been canceled.

In New York City, John F. Kennedy International Airport was closed for a couple of hours after a Bombardier jet skidded off a taxiway soon after landing. The Delta Connection flight had landed safely after arriving from Toronto with 35 passengers on board, and no injuries were reported, the Port Authority of New York & New Jersey, which runs the airport, said.

Officials in several states asked residents to use extra precautions when outdoors.

Minnesota Governor Mark Dayton has ordered all public schools in the state closed on Monday to protect children from dangerously cold weather.

Chicago schools will be open Monday despite the cold, but officials, in a statement, advised parents to "use their own discretion in deciding whether to send their child to school."

Between six inches and one foot of snow was predicted from Chicago to Detroit, AccuWeather said, while icy sleet and rain was forecast for much of the Northeast.

In case you want official advice about how to dress in such weather, here it is from the National Weather Service:

• Wear layers of loose-fitting, lightweight, warm clothing. Trapped air between the layers will insulate you.

• Outer garments should be tightly woven, water repellent, and hooded.

• Wear a hat, because 40 percent of your body heat can be lost from your head.

• Cover your mouth to protect your lungs from extreme cold.

• Mittens, snug at the wrist, are better than gloves.

• Try to stay dry and out of the wind.

And if you’re a Packers fan, make sure your Cheesehead chapeau is fleece-lined.

"It's going to be a challenge to stay warm, but we're up to it," Jacquie Tucker Braun, who planned to bring her 14-year-old son Gryphon to the game, told Reuters. She is bundling up for the game, wearing four layers on top and three layers on the bottom, along with a two pairs of socks and two pairs of gloves.

"We will see the game to the end unless there was some type of emergency," she said. "Being a Packers fan is in your blood, hereditary even."

This report includes material from Reuters.