Bah humbug: White Christmas outlook grim for most of Lower 48

Dreaming of a white Christmas? Keep dreaming.

That’s the message weather models are sending for most of the continental United States this Christmas. For the second year in a row, models show low chances of snow leading up to and on Christmas, continuing a disappointing trend – for snow lovers – tied to human-caused climate change.

Our analysis shows the odds of a white Christmas this year are at least cut in half for most major population centers in the northern half of the United States because of an abnormally warm weather pattern poised to invade North America over the next week to two weeks.

There are two key ingredients for a white Christmas – which the National Oceanic and Atmospheric Administration defines as at least one inch of snow on the ground Dec. 25 – and neither seem to be lining up this year:

• Cold air. For the week of Christmas, temperatures are forecast to be significantly warmer than average across most of the country and as much as 15 degrees to 20 degrees above average in the central United States.

• Precipitation. While there could be some, the best chances look to be in the central and southern United States, where temperatures will be the warmest and, therefore, any precipitation would probably fall as rain.

As of now, higher elevations of the Sierra Nevada and Rocky mountains are the most probable places to qualify for a white Christmas. Portions of the upper Great Lakes and interior New England have a chance to see a bit of snow on the ground Christmas morning, but even as little as one inch may be pushing it.

Climate change has been shrinking the odds of seeing a white Christmas. A Washington Post analysis of NOAA data last year showed declining chances in 18 of the nation’s 25 biggest cities during the previous decade.Below are predicted temperatures and the odds of at least one inch of snow between Dec. 20 and Dec. 25 this year in 10 cities. Also included are the recent historical odds of a white Christmas for each city.

A common theme is temperatures that are expected be significantly warmer than average, in part because of mild air associated with a strong jet stream over the Pacific Ocean. Note that this far ahead of time, temperature forecasts can be off by five degrees or so in either direction.

Bismarck, N.D.: Daytime highs are expected to reach the mid-30s to low 40s with overnight lows in the midteens to low 20s. The chance of one inch of snow is about 5% to 10%. From 1991 to 2020, the chance of a white Christmas is 71%.

Boise, Idaho: Daytime highs are expected to reach the upper 30s to mid-40s with overnight lows in the upper 20s to low 30s. The chance of one inch of snow is about 10% to 20%. From 1991 to 2020, the chance of a white Christmas is 21%.

Boston: Daytime highs are expected to reach the upper 30s to upper 40s with overnight lows in the upper 20s to mid-30s. The chance of one inch of snow is near or less than 5%. From 1991 to 2020, the chance of a white Christmas is 35% (at Blue Hill Observatory).

Buffalo: Daytime highs are expected to reach the upper 30s to upper 40s with overnight lows in the upper 20s to upper 30s. The chance of one inch of snow is about 10% to 15%. From 1991 to 2020, the chance of a white Christmas is 53%.

Chicago: Daytime highs are expected to reach the mid-40s to near 50 with overnight lows in the low to mid-30s. The chance of one inch of snow is less than 5%. From 1991 to 2020, the chance of a white Christmas is 39%.

Denver: Daytime highs are expected to reach the mid-40s to mid-50s with overnight lows in the 20s. The chance of one inch of snow is about 5% to 10%. From 1991 to 2020, the chance of a white Christmas is 35%.

Minneapolis: Daytime highs are expected to reach the upper 30s to low 40s with overnight lows in the mid-20s to near 30. The chance of one inch of snow is about 5% to 10%. From 1991 to 2020, the chance of a white Christmas is 74%.

New York City: Daytime highs are expected to reach the 40s to near 50 with overnight lows in the low to mid-30s. The chance of one inch of snow is less than 5%. From 1991 to 2020, the chance of a white Christmas is 13%.

St. Louis: Daytime highs are expected to reach the 50s to near 60 with overnight lows in the mid-30s to near 40. The chance of one inch of snow is less than 5%. From 1991 to 2020, the chance of a white Christmas is 17%.

Washington, D.C.: Daytime highs are expected to reach the mid-40s to mid-50s with overnight lows in the 30s. The chance of one inch of snow is near zero%. From 1991 to 2020, the chance of a white Christmas is 4%.

Where to go to for Christmas snow?

Even though the odds of a white Christmas are seriously depressed this year in most areas, we analyzed NOAA data from 1991 to 2020 to obtain insights into which areas have the best odds.

We found the odds of a white Christmas are below 50% to the south of 43 degrees north latitude, which is essentially anywhere south of central New England, Upstate New York, Michigan, Wisconsin, Minnesota, the Dakotas, central Wyoming, central Idaho and northern Oregon. In other words, unless you’re in the northern tier of the Lower 48, you should generally expect a brown Christmas (less than an inch of snow) more often than not.

Unsurprisingly, Alaska offers the best white Christmas probabilities. On average, the state offers an 84% chance of a white Christmas, with North Dakota at 77%, Vermont 77%, Minnesota 75% and Maine 74%, rounding out the top five white Christmas states.

It’s not all just about latitude, as elevation above sea level can also play a significant role. Below 1,000 feet, especially in the nation’s southern tier, odds of a white Christmas are minimal – less than 10% nationwide. In the highest elevations, around 8,000 feet or higher, a white Christmas becomes close to a certainty.

Although odds of a white Christmas have never been great for much of the nation, they are going down in many places as the Earth warms, dropping by 4% to 6% in recent years. For example, the chance of a white Christmas in Denver dropped from around 40% in 2010 to near 35% in 2020, while in Washington, D.C., white Christmas odds fell from around 8% to just over 4% over the same period.