News brief
You've probably heard these lyrics — "I’m dreaming of a white Christmas" — about 100 times by now. But the chances of it actually happening vary, depending on where you’re located in the Mountain West.
Climate experts from the National Centers for Environmental Information gathered data from nearly 15,000 weather stations and published an interactive map looking at the probabilities of where it might be snowing – or not – on Christmas Day. It’s based on data showing an inch of snow cover on December 25 between 1991 and 2020.
"This isn't like a forecast or anything like that," said Dan McEvoy, a climatologist at the Desert Research Institute in Nevada. "It's just based on climatology. And it's telling you about the odds of having a white Christmas based on observations."
Some patterns make sense to those who have lived in the West. At high elevations or in mountain ranges — like Sierra Nevada and the Rockies — there's a high probability of a white Christmas — 60% and above. But as you go south, snowfall is more rare.
"You tend to find the odds start to decrease, " said Michael Palecki, product lead for the U.S. Climate Normals data in this map. " And so by the time you're in southern Utah or southern Nevada, your odds are pretty small, 10% or 20% of having a white Christmas."
Some states have better odds than others. Idaho has seen an increase in odds, up to 5% more in some areas, according to Palecki’s analysis of the last 30-year estimate. Yet, these observations are all relative to winter storms.
"The forecasts can change very quickly with winter storms," McEvoy said. "And you might have no snow on Christmas Eve. And it could very well happen that you wake up on Christmas Day with a white Christmas if the right set up comes along."
Areas in the Great Basin and cities at lower elevations are a little harder to predict since they usually have ephemeral snow–or snow that falls and melts in less than 60 days, McEvoy says. He lives in Reno and believes their chances of a white Christmas are slim.
"There is a few inches of snow that fell, and it's been really cold," he said. "But the forecast going into Christmas week is a pretty substantial warm-up, about 10 degrees warmer than it's been over the last week. And so I would expect … that snow will be gone by Christmas."
Palecki said a white Christmas comes down to two factors: precipitation and temperature. But recently, it’s been too warm for snow in most western states due to climate change. Even mountain areas that are used to heavy snowfall are seeing less.
"The temperatures in December have risen in the last decade or two, quite a bit, a degree or two in Fahrenheit terms," Palecki said. "That kind of begins to chip away at the odds of having a white Christmas."
Palecki warns that some areas may not see a white Christmas if our world continues to warm up.
"On the southern end of the snow shield or on the east or West Coast, where your odds of getting a white Christmas are smaller, like 30% or 25%, well, those areas are going to be affected more by climate change coming up in the next few decades," he said. "And so your odds might actually go down to having a pretty infrequent white Christmas in these areas."
Regardless, Palecki says changes in the overall odds are not that significant, and there will be white Christmases for several decades. So it could still be just like the ones we used to know.
"I don't think it's going to be a distant memory or anything," he said. "It's not going to be some singular date after which you just don't have them anymore. They're always going to be a chance."
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, the O'Connor Center for the Rocky Mountain West in Montana, KUNC in Colorado, KUNM in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.
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