In Chicago and much of the rest of the Midwest, several days of sub-zero temperatures have taken their toll. And on Tuesday, a number of Southern cities will be feeling the chill, as well. NBC's John Yang reports.

A brutal winter freeze began to descend on the Deep South early Tuesday with a huge swath of the region in the crosshairs of a storm that forecasters called "potentially paralyzing."

The storm was still in its infancy at 3:30 a.m. ET but meteorologists at The Weather Channel said they already had reports of sleet and freezing rain in parts of Texas and Louisiana.

Schools from the Lone Star State to Florida earlier announced that they would close Tuesday, and the storm is playing havoc with air travel. As of 6:45 a.m. ET, airlines had cancelled 2,665 flights across the country, with Atlanta's Hartsfield–Jackson and Houston's George Bush Intercontinental airports bearing the brunt, according to FlightAware early Tuesday.

Winter storm alerts have been issued by the National Weather Service all the way from central Texas eastward through the Gulf Coast into Georgia, the Carolinas and far southeast Virginia.

Nearly 60 million people are affected by a cold weather warning or watch Monday night. By Friday, however, temperatures will rise above normal for much of the country. NBC News' Al Roker reports.

Weather Channel meteorologist Nick Wiltgen described it as a "potentially paralyzing winter storm." And the forecaster’s winter weather expert, Tom Niziol, said the South was in for weather "that many parts have not seen in years" — perhaps the biggest winter weather event in a generation.

The nasty weather will reach so far south that Johnson Space Center, in Houston, said it would be closed.

The the biggest snow threat lay in eastern and central Texas, including Houston, and stretched to southeast Virginia. Eastern North Carolina and southeast Virginia would have the greatest chance of getting more than six inches of snow, according to The Weather Channel.

The winter storm is traveling south-eastwards and the wintry mix will dip as low as the Florida Panhandle on Tuesday. By Wednesday, it will have started to bend up the East Coast, where it will travel as far north as Providence, Rhode Island, before moving offshore by lunchtime.

Several factors will decide whether ice and snow will stick to the roads across the region, said Kevin Roth, lead meteorologist at The Weather Channel. Temperatures may not be as low as in the North, where this type of weather is more common, but Southern states are far less prepared to deal with the conditions.

Two other elements are at play: The South has been experiencing below-average temperatures for much of January, but with it being more than a month after the Winter Solstice the sun angle is higher and therefore between at melting ice and snow.

For merchants in Louisiana, business was booming Monday as residents flocked to hardware and grocery stores.

"I'm almost out of all the electric heaters, the propane heaters, and a lot of propane," Lance Butler, owner of Sullivan's Hardware in the town of Central, told NBC station WVLA of Baton Rouge. "It's just about like it would [be] if it was before a hurricane coming," Butler said.

Jennifer Shephard / The Elkhart Truth via AP A man waves to thank the driver of a passing car for giving he and a friend room on the road as they walk in Elkhart, Ind., during heavy snow Saturday.

Meanwhile, the Great Lakes shivered again under wind chills that approached 50 degrees below zero. School officials in major cities across the region — Cleveland, Cincinnati and Columbus, Ohio; Chicago; Milwaukee and Madison, Wis.; Detroit; Minneapolis and Duluth, Minn.; and Indianapolis — said classes would be canceled Tuesday.

The University of Michigan said it would be closed Tuesday — the first time that's happened because of weather in 35 years.

"We're going to be talking about some seriously cold mornings," with temperatures as much as 35 degrees below normal for what is already historically the coldest time of the year, Weather Channel meteorologist Alex Winter said.

Lows overnight into Tuesday were forecast to plummet to 5 degrees below zero in Detroit and 20 below in Chicago, where school was already called off for Tuesday and whose airports scrapped more than 530 flights Monday.

The frigid weather was arriving just as a nationwide shortage of propane — which about 14 million Americans use to heat their homes — was reaching critical proportions.

With prices more than doubling from $2 a gallon to more than $4 last week, the governors of Minnesota and Illinois declared states of emergency Monday, urging residents to cut back and regulators to lift restrictions on shipping to their states.

The demand from Midwestern states threatened to strain supplies in otherwise well-stocked Southern states, said Greg Rodes of Southern Flame Propane in Lexington, S.C.

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