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 snowstorm warning was in effect for 31 million people - from southern Texas east through Georgia and north to the Carolinas and into Virginia - until Wednesday morning, the National Weather Service said.

A rare winter storm churned across the U.S. Gulf Coast on Tuesday, breaking snowfall records more than a century old in a southern region where flurries are unusual, as much of the United States remained in a dangerous deep freeze.