December's weather has been one for the books, with more than 2,800 temperature records already broken. Some 84 percent of the U.S. population has experienced temperatures that average over 5 degrees warmer than usual, according to The Weather Company.
Much of the warm weather is due to a phenomenon known as El Nino, which is transporting warm weather from the Pacific across the United States, which has delighted some.
But it's not all sunny news. In some cases the eastern U.S. has been experiencing temperatures as high as 40 degrees above average, while the south and mid-Atlantic have experienced deadly tornados and flash flooding. At the same time, Northern California has had snowstorms leading to treacherous conditions on the roads.
"We're seeing warm temperatures the likes of which we've never seen before," said Paul Walsh, The Weather Company's vice president of weather strategy, told CNBC's "On the Money" in an interview.
What's causing the unusual weather? Part of it is El Nino, which occurs every 7 to 8 years. But Walsh said climate change cannot be completely discounted.
"The effect of climate change is actually amplifying or juicing the impact," he added.
The unusual weather and its impacts are here to stay. Walsh expects the southern half of the U.S. to stay cold and wet, while the northeast and Midwest will start 2016 with mild weather.
"We're going to continue to see the weather playing a big role in shaping the economy and shaping consumer spending as we move into '16," Walsh said.