An arctic air mass sprawling across the eastern, central and parts of the western U.S. on Monday will channel temperatures 20-30 degrees below already historically cold January averages and was poised to slam parts of the South with a disruptive winter storm.

Most of the United States is being assailed with extreme winter weather this week as Arctic air blasts south from Canada, snow tracks up the Northeast coast and a potentially crippling winter storm takes aim at the South.

A winter storm warning was issued by the National Weather Service on Monday at 3:53 a.m. valid from Tuesday 6 a.m. until Wednesday 6 a.m. for Choctaw, Washington, Clarke, Wilcox, Monroe, Conecuh, Butler,

The heaviest snow was expected to fall in New Jersey between 4 and 9 p.m. Sunday, with totals of up to 8 inches.

Winter storm warnings have been issued for New York, New Jersey and Connecticut with the entire region bracing for snow.

The snow started falling in the early afternoon and will become heavier in the early evening, the National Weather Service reported.