A forecast map reveals which states can expect to see “persistent cold” in the weeks ahead, after experts said the polar vortex would unleash waves of icy air across parts of the U.S. through January.

The stratospheric polar vortex, the winter engine that traps Arctic cold high above the North Pole, is entering its seasonal collapse. What’s left is the lower-level polar vortex core, lingering over ...

"Another shot of arctic air is on the way for next weekend," the NWS said.

The majority of the United States will experience chilling temperatures due to a blast of arctic air from Canada. The Midwest, Mid-Atlantic and Southern U.S. are expected to see below-freezing ...