Over the next few days, 220 million people living in the continental US – about 75 percent of Americans – will see temperatures drop below freezing as Arctic air blasts southward.

“Back to back cold fronts will slice through the eastern two-thirds of the country to deliver one of the coldest arctic air intrusions in recent memory,” writes the National Weather Service (NWS) on its website. "Frigid temperatures and bitterly cold wind chills” will likely result in widespread record lows across much of the country, culminating in a combination of winter storm and wind chill warnings, watches, and advisories across the central part of the country.  

It could be the coldest burst of air in a generation, CNN reports. 

“Not only is brutal cold invading the central parts of the country, accumulating snow and freezing roadways all the way into the deep south could make travel dangerous through tomorrow morning,” the NWS wrote yesterday in a Tweet. 

Known as the polar vortex, the abnormally cold weather system is a result of a change in wind patterns across northern polar regions. A circulation of strong winds normally surrounding the northern pole typically moves in a counterclockwise fashion, locking freezing air in the Arctic parts. This low-pressure system always strengthens in the winter, at which point it expands and can occasionally send Arctic air southward. The NWS reminds that although this phenomenon has gained media attention in recent years, the polar vortex is not totally new. Notable incidents occurred in 2014, as well as those in 1989, 1987, 1982, and 1977, and it’s not always confined to the US. Asia and Europe have also experienced dramatic polar vortexes.

Already, the deadly cold has resulted in two fatalities in the US and, with the coldest weather yet to come, experts are advising people to stay aware and prepare.

“People exposed to extreme cold are susceptible to frostbite in a matter of minutes. Areas most prone to frostbite are uncovered skin and the extremities, such as hands and feet. Hypothermia is another threat during extreme cold. Hypothermia occurs when the body loses heat faster than it can produce,” warns the NWS on its website.

You can find more helpful (and potentially life-saving) information here.