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

Southeast Texas is bracing for Winter Storm Enzo, prompting airport closures in Houston and widespread travel disruptions.

If it warms up enough during the day Tuesday, it’s possible for some of that accumulated snow and ice to melt, but snow or ice that sticks around Tuesday will refreeze Wednesday night, when temperatures are expected to plunge into the 20s or teens, Platt said.