The most unusually cold air in the Northern Hemisphere will be over the United States early next week, bringing dangerously ...

The polar vortex will soon elongate over North America with a dangerous cold moving into sections of Canada and the U.S.

Some areas of the U.S. may see temperatures as low as -20 or -30 degrees early next week as arctic air from Siberia rolls in.

As they describe it, the polar vortex circles the north pole counterclockwise. the polar jet stream circles at a lower level of the atmosphere, which usually keeps Arctic air corralled in the middle.

(AP) — The plunging polar vortex brought subfreezing temperatures ... along Texas' border with Mexico, to 31 degrees (minus 0.5 Celsius), with an expected wind chill factor ranging from 0 ...

A mix of sleet, snow and freezing rain is expected to fall on a stretch of the U.S. from New Mexico to Alabama starting ... with employees working remotely. The polar vortex of ultra-cold air ...

These severe cold events occur when the polar jet stream – the familiar jet stream of winter that runs along the boundary ...

Snow and winds are likely to trigger flight cancellations and cause headaches for people traveling to DC for Inauguration Day ...