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

Large stretches of the U.S. await one of the season’s first blasts of wintry weather as temperatures dropped in the Northern Plains and snowstorms developed across the Great Lakes.

A derecho, characterized by a line of thunderstorms producing severe winds and damage over a large area, swept across the Northern Plains and Upper Midwest.

A Montana judge on Friday said a climate change lawsuit from young people challenging the state’s pro-fossil fuel policies will proceed to trial despite efforts by the state to derail the case.

The KPRC 2 Severe Weather Team is monitoring severe storms moving through central and east Texas Friday evening.