More than 220 million people across the United States are facing dangerous cold that will also open the door for a potentially historic and crippling winter storm that could deliver snow as far south as Florida and the Gulf of Mexico.

A rare winter storm is sweeping the Gulf Coast, bringing unprecedented snowfall in parts of Texas all the way to northern Florida, a region that's not accustomed to such frigid conditions. Thousands of flights were canceled or delayed on Tuesday due to the hazardous conditions,