A polar vortex is slated to sweep most of the continental US bringing winter storm warnings and a hazardous freeze to millions.

Like much of the U.S., Wisconsinites woke up Tuesday morning to bitter cold conditions. Many schools and colleges throughout the Milwaukee area closed as the area braced for the dangerous freezing temperatures.

Abnormal weather events and severe winter storms could be caused by a disrupted polar vortex. Find out here how the polar vortex affects the weather.

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.