It's cold. Really cold. And for much of the eastern United States, there's no relief in sight.

President Donald Trump tweeted from Florida Thursday that maybe the East Coast would benefit from some climate change:

In the East, it could be the COLDEST New Year’s Eve on record. Perhaps we could use a little bit of that good old Global Warming that our Country, but not other countries, was going to pay TRILLIONS OF DOLLARS to protect against. Bundle up! — Donald J. Trump (@realDonaldTrump) December 29, 2017

But why is it so cold? Perhaps more importantly, how long is it going to be so cold?

Cold Weather, Warm Climate

Weather Versus Climate Change Neil deGrasse Tyson breaks down the differences between weather and climate change.

It's not unusual for winters in the U.S. to be frosty; late December through January are the nation's coldest weeks. It is strange, however, that these spells are lasting as long as they are, says Minnesota-based meteorologist Eric Holthaus.

Under normal conditions, a cold spell might go on for three or four days. Right now, some spots in the country are seeing ten-day stretches of cold.

"The longevity of it is a bit unusual," Holthaus says from Saint Paul, where temperatures have been hovering around zero degrees Fahrenheit. "It's just a really localized thing that's happening right now."

Warm Elsewhere

"We're having record lows and record highs at the same time," Holthaus says.

"Winters could be harsher," Michalak told National Geographic in July. "By emitting greenhouse gasses, we're not just warming temperatures, we're perturbing the Earth's entire system."

Weather models can only predict temperatures into the next week or two, and the models are still showing cold waves across some parts of the U.S. Holthaus estimates the cold spells could last about a week to ten days, but it's too soon to say if this long stretch of cold is being caused by climate change. (Take this quiz to see how much you know about winter weather.)

Why It’s Hard to Forecast the Weather

"It's really difficult to say for certain if this exact weather pattern today would have happened the same way without climate change," Holthaus says. "It's really irresponsible to say that climate change is not affecting weather everywhere on Earth."