The coldest weather of the season to date will be due to a phenomenon called a polar vortex, an upper-level jet stream that typically circulates around both the North and South Poles, but can push cold winds down into the U.S. and Canada when it weakens and expands.

The freezing temperatures will move eastward, reaching locations like Philadelphia, where daytime highs will only reach the upper teens. The polar vortex is a gigantic circular upper-air weather pattern in the Arctic that envelops the North Pole.

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,

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,