A rare frigid storm is charging through Texas and the northern Gulf Coast, blanketing New Orleans and Houston with snow, closing highways and grounding nearly all flights.

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.

The snow storm could hit over a dozen states through Wednesday, including Texas, Louisiana, Mississippi, Alabama, Florida, Georgia and the Carolinas.