Record Winter Heat in the U.S. and Climate Change Impacts

No U.S. states had a record cold winter. Nine had a record hot one. Though it may surprise East Coasters, the story of this winter was not record cold but record heat. For those in the eastern half of the country, this winter seemed like an endless slog of frigid temperatures and stubbornly persistent snow piles. So it may come as a surprise to many that nowhere in the U.S. had a record cold winter this year. Nowhere even came close. What did set records was heat. The western half of the country spent the winter baking—nine states had their hottest winter ever and five their second-hottest—which worsened drought conditions and has raised the risks of damaging wildfires come spring and summer. So much of the country was so warm that despite the cold in parts of the east, it was the second-warmest winter on record for the contiguous U.S. in the past 131 years. And for much of the eastern U.S., the winter was actually around average. Eight states had below average temperatures, but those were only in the lower third of the record books. The reason it felt so cold out east and so hot out west is the same: climate change. Winter is the fastest-warming season, and cold snaps are shorter and less cold than they used to be. An analysis of more than 200 locations around the U.S. by the nonprofit Climate Central showed that the coldest winter temperatures today are seven degrees Fahrenheit (four degrees Celsius) warmer on average than they were in 1970. So when we do get a spate of chilly weather, it feels colder than it did in the past because we’re not as acclimated to it. It’s a longer-term version of how 60 degrees F (16 degrees C) feels amazingly warm after a cold winter but refreshingly cool after a hot summer—it’s all a matter of what your body has adjusted to. Climate change also means that even when the weather setup brings Arctic air surging southward, it’s not as cold as it once was, making cold records increasingly rare. “When folks complain that all they hear about is record warmth (‘Why do you never talk about the record cold?’)—well, this is why!” Swain wrote in a recent blog post. “Record cold has become a truly rare condition, whereas record warmth is now occurring with remarkable and disconcerting frequency.” Heat records will keep piling up as long as heat-trapping greenhouse gases continue to accumulate in the atmosphere. And the west has more record-shattering temperatures in store: a heat wave in the region in mid-March could send the mercury soaring above 100 degrees F (38 degrees C) in some places.