Coldest wind chills in years threaten most of the US, with unusual snowfall expected in the South | Weather [Video]

(CNN) — More than 170 million people across the United States, from the Mexican border to the Canadian border are under cold weather alerts ahead of a crippling winter storm expected to sweep through the south from Texas to Georgia, including the Gulf Coast.

The storm – in combination with frigid air – will bring early this week historic snowfall, freezing rain, icy roads and other major travel disruptions to southern cities where harsh winter weather is rare.

The storm is taking place amid a wider extreme winter spell across the country, originating from an Arctic blast moving south from Canada and dropping temperatures 20 to 30 degrees below average across most of the Rockies, Central and Eastern US.

Across the North, multiple cities like Chicago, Minneapolis, Detroit, New York City, Washington, DC, Boston and Philadelphia could go days without seeing a high temperature climb above freezing.

Southern cities like Houston, Atlanta, …