Around 40 million people in the U.S. are under a winter storm warning from an unusual blast of severe winter weather.

Snow is likely to fall across South Texas tonight into Tuesday. North Texas will remain mainly dry and quite cold.

Amid a dangerous arctic blast over much of the U.S. this week, snow and ice may bring major travel disruptions and power outages in the South, forecasters warned.

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.