Baby, its cold outside, and its about to get even colder for much of the United States.A polar vortex of brutally cold air that normally circles the Arctic will be spilling southward, starting this weekend and into next week, bringing below-freezing temperatures to many parts of the country.More than 120 million people could face bone-chilling conditions, with some 50 million Americans in 30 states facing temperatures below minus-10 degrees Fahrenheit.The arctic blast is due to first hit the Rockies and Great Plains Friday, reaching the Deep South and Great Lakes Saturday night, and the Eastern Seaboard by Sunday night, producing the coldest air of the season thus far, the National Weather Service (NWS) posted on its website midday Friday.Screenshot via Climate.govStarting Saturday into Tuesday, the Rockies, Northern Plains, and Upper Midwest could have minimum wind chills of 30 to 50 below zero. Sub-zero wind chills are also forecast to reach the Southern Plains and Ohio Valley on Sunday night into Wednesday, while hazardous cold weather is likely along the Gulf Coast and Southeast through much of next week, per the NWS.Cold winds and snow could strain vital infrastructureDangerously cold winds and plummeting temperatures could cause pipes to freeze and burst, possibly affect the power grid, and increase the risk of hypothermia and frostbite, according to the Washington Post. Nearly 80 million Americans will be below zero degrees by next Tuesday when extremely cold Canadian/Siberian Arctic air descends on the Lower 48, meteorologist Ryan Maue posted on X. The nationwide average low temperature will be only 6F.Meteorologists at AccuWeathersaid on Sunday, a snowstorm is expected to be headed to the Northeast, hitting Boston, New York City, Philadelphia, and Washington, D.C., dump[ing] enough snow to shovel and plow in areas from West Virginia to Maine.The weather is likely to trigger traffic problems and a surge in flight cancellations, which is bad news for those traveling to Washington, D.C., for President-elect Donald Trumps inauguration on Monday.Trump said he has moved his swearing-in ceremony indoors due to the forecast, posting on Truth Social that the Inauguration Address, in addition to prayers and other speeches, to be delivered in the United States Capitol Rotunda, as was used by Ronald Reagan in 1985, also because of very cold weather.