This just in: It gets cold in the winter.

Now, with that (staggeringly obvious) statement made, according to the forecast, much of the contiguous 48 states are about to get really, really cold - and stay that way for a while. Yes, folks, the infamous polar vortex is back, and it looks like it's settling in for an extended visit.

January is shaping up to be the coldest in a decade as the polar vortex dips south across the eastern half of the United States — shocking a nation that has enjoyed an unusually balmy end of the year.

“It’s going to get cold, and then very cold,” a Fox Weather meteorologist told The Post Monday.

“Based on the latest long-range data, this January has the potential to be the coldest since 2014,” they added.

Like that annoying second cousin who drops in for your New Year's Eve party and ends up crashing on your couch for a week, the vortex will be around for a while:

Temperatures are expected to begin dropping from the Rocky Mountains to the East Coast around Thursday, but the real plunge will set in sometime between seven and 14 days from now.

The plunge will bring wind chills across the Midwest dipping below zero, “exceptionally cold” temperatures down to 20 degrees below average in some places, and freezing conditions setting in as far south as the Gulf Coast and even into Florida — though it is still too early to forecast exact temperatures.

And there is a “pretty good chance” the vortex will bring with it “significant winter storms,” Fox Weather cautioned.

Here in the Great Land, we're having an unusually mild winter so far - it's tempting to point out that folks from places like Minneapolis, Denver, Omaha, or even St. Louis may want to consider a visit to Alaska to warm up. It's not often we get to make that kind of an offer.

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As an Alaskan - when we get temps in double-digits below zero, we call it "Tuesday" - I'm inclined to offer some advice to folks who may not commonly experience these kinds of temperatures.

First: When you're going somewhere, check road conditions before you leave. And dress, not for the trip, but for the weather. Your car may break; a slick road may send you into the ditch. If that happens, you'll be grateful for the warm clothes.

Second: Speaking of your car, make sure you have good tires, make sure your windshield washer reservoir is full, and make sure you have a solid, long-handled ice scraper. If you have an engine block heater, keep your vehicle plugged in.

Third: Don't just depend on a good winter coat, although that's important. Warm boots are important. So are good gloves, a warm hat, and a scarf. A good base layer is important, too - a good turtleneck isn't the worst idea. You lose a lot of heat through the neck and head.

Fourth: Don't fall for the old bit about a tot of brandy or some other adult beverage to deal with the cold. Alcohol actually makes you more susceptible; that brief flush of warmth is due to your body shedding heat, which is the opposite of what you'll want to be doing.

These things can be life-savers:

During the 2014 January polar vortex, more than 20 people across the country died from the cold as places like Georgia — which rarely see serious cold — dealt with lows under 10 degrees Fahrenheit.

Whether or not you were ever a Boy Scout - be prepared. Stay warm! Stay indoors if you can. And be patient: Spring will be along before we know it.