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

A rare winter storm charging through Texas and the northern Gulf Coast on Tuesday has closed highways and airports and prompted the first blizzard warning for southeast Texas and southwest Louisiana.

Heavy snow and freezing temperatures are hitting parts of Texas and the Gulf Coast, causing travel disruptions and prompting a number of Southern governors to declare states of emergency. Winter weather — including low temperatures and storms — involves a number of risks,