A polar vortex dipping down from Siberia will bring a cold front with frigid temperatures to nearly 300 million Americans. See maps of the arctic blast.

According to the National Weather Service, a polar vortex will impact most of the country this weekend, here is what you need to know.

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.