The agency forecasts snow accumulations of 12 to 18 inches during this time for areas above 6,000 feet, while areas over 4,000 feet should expect 3 to 6 inches. On Saturday, wind gusts could reach 50 miles per hour in speed, with travel becoming "very difficult to impossible."

Winter storm warnings are in place in several states with heavy snow, freezing rain and dangerously cold temperatures expected.

Snow totals in Louisiana have broken records. Parts of Florida, Texas and Georgia have also accumulated several inches of snow.

Follow NBC News live updates for the latest coverage of the freezing winter weather affecting large swaths of the U.S., from the Midwest to the South.

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.

I’ve been convinced that we are about to experience a very serious and dangerous weather episode,” Houston Mayor John Whitmire said Sunday.

Delivery times for post in over half the country could be impacted due to hazardous weather, the U.S. Postal Service said.

A polar vortex is slated to sweep most of the continental US bringing winter storm warnings and a hazardous freeze to millions.

It’s been a somewhat mild winter so far, but things have certainly changed as winter weather makes its presence known across the Lower 48 states ... The National Weather Service said ...

A polar vortex is forecasted to blanket most of the continental United States in the coming ... according to the National Weather Service. In a tweet from the service, the strong cold front ...

Memphis is set to get hit with a cold weather system early this week that could drop wind chills to as low as 5 degrees.

The wind chills as low as 15 degrees are expected for parts of Alabama, Georgia and Florida Thursday evening into Friday morning.