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.

Add Yahoo as a preferred source to see more of our stories on Google. This winter’s harsh run is intensifying, with some of the coldest air so far this season plunging into New Hampshire this weekend ...

A fresh blast of Arctic air is poised to spill across a wide swath of the United States, and the latest polar vortex map makes clear which regions are most exposed. Forecast models show a sharp ...

A mass of Arctic air from Canada is bringing brutally cold temperatures to the northeastern United States. New Hampshire is under an Extreme Cold Watch, with wind chills expected to reach 20 to 30 ...