SIOUX FALLS, S.D. — The deep freeze expected in the Midwest and the South will be one to remember, with potential record-low temperatures heightening fears of frostbite and hypothermia. The frigid air will begin Sunday and extend into early next week, funneled as far south as the Gulf Coast.
It hasn’t been this cold for decades — 20 years in Washington, D.C., 18 years in Milwaukee, 15 in Missouri — even in the Midwest, where bundling up is second nature. Weather Bell meteorologist Ryan Maue said, ‘‘If you’re under 40, you’ve not seen this stuff before.’’
Blame it on a ‘‘polar vortex,’’ as one meteorologist calls it, a counterclockwise-rotating pool of cold, dense air.
‘‘It’s just a large area of very cold air that comes down, forms over the North Pole or polar regions . . . usually stays in Canada, but this time it’s going to come all the way into the eastern United States,’’ said meteorologist Phillip Schumacher in Sioux Falls, S.D.
The predictions are startling: 25 below zero in Fargo, N.D., minus 31 in International Falls, Minn., and 15 below in Indianapolis and Chicago. At those levels, exposed skin can get frostbitten in minutes and hypothermia can quickly set in as wind chills may reach 50, 60, or even 70 below zero.
Even wind chills of 25 below zero can do serious damage, according to meteorologist Scott Truett in St. Louis.
‘‘Those are dangerous levels of wind chill,’’ he said of the expected wind chill in Missouri at daybreak Monday. ‘‘A person not properly dressed could die easily in those conditions.’’
Already, parts of New England dropped into the negatives early Saturday, with East Brighton, Vt., seeing 30 below zero just after midnight and Allagash, Maine, hitting minus 36.
Snow will reduce the sun’s heating effect, so nighttime lows will plummet because of the strong northwest winds.
More snow is expected in parts of the central Midwest and South starting Saturday night — up to a foot in eastern Missouri and southern Michigan, 6 to 8 inches in central Illinois, 8 or more inches in western Kentucky and up to 6 inches in parts of middle Tennessee.
Sunday’s NFL playoff game in Green Bay, Wis., could be among the coldest ever played — a frigid minus 2 degrees when the Packers and San Francisco 49ers kick off at Lambeau Field. Medical experts suggest fans wear at least three layers and drink warm fluids.
Minnesota has called off school Monday for the entire state — the first such closing in 17 years — as well as the Wisconsin cities of Milwaukee and Madison.