A strong polar vortex in the stratosphere has brought subzero temperatures to the Midwest, Mid-Atlantic and deep into the South.

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

In Indiana, around zero degrees was likely, the map showed, with temperatures of around three degrees possible in Northern Maine. Northern Georgia would see temperatures around 16, and in Colorado, the map showed that some areas would see -9.

Arctic air has brought chilling temperatures as low as 12 degrees in New York City on Monday night but are we in a polar vortex? A polar vortex settled its way over New York City and New Jersey following Sunday’s snow storm,

Meteorologist Travis Clark-Smith dives into what caused our recent cold snap.

This blast of frozen temperatures is tied to a polar vortex... but what is that? Air spins around the notoriously cold North and South Poles. When the air is spinning fast, it's stable, but when it is weakest,