The southeastern U.S. has plunged into record-low temperatures, affecting 18 million people under a freeze warning across Alabama, Florida, and Georgia.

Snowy roads led to hundreds of crashes throughout Virginia and North Carolina, including a series of crashes on an interstate highway involving more than 50 vehicles.

Heavy rain is falling across Southern California, creating deluges of water and mud on roads at the bottom of hillsides left barren by recent wildfires.

Heavy snow and freezing rain from Kentucky to the nation's capital caused hundreds of crashes and left tens of thousands of residents in the dark.