Americans from the western plains to the Eastern Seaboard are bracing Monday for record low temperatures and wind chills down to 60 below zero as a polar vortex thrusts frigid arctic air over two-thirds of the United States.
The National Weather Service on Sunday issued wind chill warnings, watches or advisories affecting 115 million residents. By Tuesday, about 1.5 million square miles of the lower 48 states are expected to face wind chills of zero degrees or below, the Washington Post said.
The bitter cold is hampering air travel. More than 2,400 flights have been canceled to or from U.S. airports for Monday, CNN said, citing the Flightaware.com tracking website.
Monday's high temperatures aren't expected to climb above zero across most of the Midwest. When expected wind speeds are factored in, it could feel like 24 below zero in St. Louis, 34 below zero in Chicago and minus 55 in Duluth, Minn., CNN reported.
Officials have canceled school in St. Louis, Chicago, Detroit, Indianapolis and Milwaukee in the face of the extreme forecasts. Minnesota Gov. Mark Dayton closed school across the entire state "to protect all our children from the dangerously cold temperatures," the Telegraph said. The governors of Michigan and Illinois urged residents to remain indoors.
Heading South wouldn't provide much comfort. Temperatures in the Atlanta area dropped from the low 50s at midnight to the low to mid 20s by dawn, the Atlanta Journal-Constitution said. Gusting winds dropped the wind chill to 8 degrees.
Hard freeze warnings have been posted from eastern Texas to Florida. Subzero lows are forecast as far south as Alabama. Tennessee, expecting the lowest temperatures in nearly two decades, declared a state of emergency on Monday.
Bitter temperatures are expected spread to the mid-Atlantic later Monday, then extend to New England and the Southeast, NBC News said.
The culprit is a "polar vortex," described by the Telegraph as a persistent large-scale cyclone that usually swirls over the north or south poles. When a polar vortex splits apart, its cold air gets flung a long way, in this case far to the south.
The frigid polar vortex already was holding sway Sunday night in Green Bay, Wis., as the Packers hosted the San Francisco 49ers in a National Football Conference playoff game. Some tailgating fans fired off two grills, one for food, the other for warmth. In the stands, fans were treated to complimentary coffee, hand warmers and hot chocolate.
It grew so cold overnight that both engines froze on an Amtrak train from Detroit to Chicago, leaving passengers stalled on the track near Kalamazoo, Mich., for about nine hours before another train arrived, NBC said.
Poor visibility from blowing snow left the Southern Illinois University men's basketball team stranded on the side of Interstate 57, CNN reported. The driver had pulled over to let visibility improve, but then couldn't get traction when he tried to pull back onto the highway, SIU Athletic Director Mario Moccia told the network.
Here's more from the Associated Press: