Millions of people across the northern Gulf Coast braced Tuesday for a rare winter storm that’s expected to scatter heavy snow, sleet and freezing rain around the Deep South as a blast of Arctic air plunges much of the eastern U.S. into a deep freeze.

Temperatures could dip to record lows along the Gulf Coast and into the Tennessee Valley, the National Weather Service warned.

Around 40 million people in the U.S. are under a winter storm warning from an unusual blast of severe winter weather.