January is shaping up to be the coldest in a decade as the polar vortex sinks southward over the eastern half of the United States – shocking a nation that experienced an unusually mild end to the year.

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

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

Temperatures from the Rocky Mountains to the East Coast are expected to drop around Thursday, but the real plunge will occur sometime in seven to 14 days.

The crash will cause winds to drop below freezing across the Midwest, temperatures to be “exceptionally cold” as much as 20 degrees below average in some locations, and temperatures as far south as the Gulf Coast and even Florida Freezing temperatures are coming – although it is still early to predict exact temperatures.

And there’s a “pretty good chance” the twister will bring “significant winter storms,” ​​Fox Weather warned.

“The best window for these winter storms would be mid to late next week,” they said, adding that the Southeast could even see snow or ice.

While most polar vortex forecasts are often unpredictable, Fox Weather said this round of cold weather is different.

“This is a very confident forecast. Weather models everywhere are screaming at us that this really cold air is on the way,” the meteorologist said.

The cold is expected to continue throughout January, with relief once February is over.

Such crashes occur when the air currents that hold cold air over the North Pole – the polar vortex – weaken and the freezing Arctic air slides south, pushing the vortex down with it.

That means Arctic air itself is blowing over the U.S., while pressure changes and the movement of the polar vortex whip up strong winds, creating a perfect recipe for wintry weather.

The cold will ease as the vortex stabilizes again and pushes Arctic air back north.

January’s frost comes after December started cold but ended unseasonably warm across most of the country.

This duality resulted in temperatures that were essentially December average, but in parts of the West the warmth continued throughout the month, bringing the average to over 13 degrees above normal.

During the polar vortex in January 2014, more than 20 people died from the cold across the country, as places like Georgia – which rarely experiences serious cold – struggled with low temperatures below 10 degrees Fahrenheit.