A winter storm prompted a National Weather Service office in Louisiana to issue a first-ever blizzard warning. The storm is causing dangerous conditions from Texas to North Carolina.

Louisiana, Mississippi, Alabama, Georgia, Florida also under winter storm warnings: snow, sleet, freezing rain, icy conditions expected - Anadolu Ajansı

Houston’s two major airports, George Bush Intercontinental and Hobby, are also closed Tuesday, while Hartsfield-Jackson Atlanta International Airport, the world’s busiest, is pretreated roadways and airfield surfaces in preparation for the winter weather, according to spokesperson Andrew Gobeil.

Around 40 million people, primarily across the southern US, were under some type of weather hazard, March Chenard, a meteorologist with the NWS, told BBC's partner CBS News. Another 170 million people from the Rockies to points eastward were under an extreme weather warning or cold weather advisory.

A once-in-a-generation winter storm event is underway in the southern United States, which is forecast to have significant impacts to cities and residents unaccustomed to winter weather

A polar vortex dipping down from Siberia is bringing a cold front with frigid temperatures to millions Americans. See maps of the arctic blast.

As heavy snow, sleet and freezing rain hit parts of the Deep South, a blast of Arctic air plunged much of the Midwest and the eastern U.S. into a deep freeze.

A rare winter storm churned across the U.S. Gulf Coast on Tuesday, bringing heavy snow, ice and wind gusts to a region where flurries are unusual, while much of the United States remained in a deep freeze.