How common is December snowfall in the nation's capital?

 

December 2017 snow in Germantown, MD (Photo Credit: Susan Granzow)

The nation’s capital averages 1.7” of December snowfall. It's no secret that snow has been scarce in the nation's capital recently. That's part of a more than decade-long trend of below average snowfall.

Washington, D.C. averages 13.7" of annual snowfall, according to NOAA. That's based on NOAA's running 30-year average and is updated every decade. The current 30-year average was updated in 2021 to reflect the period of 1991-2020, which replaced the previous data set of 1981-2010. Essentially, the decade of the 2010s replaced the 1980s and Washingtonians saw noticeably less snow in the 2010s than the 1980s (D.C.’s previous annual snowfall average was 15.4”).

D.C.'s last snowier than average winter, overall, was in 2018-2019 (16.9"). Snowfall has been quite meager since then with only two snowier than average months in the nation's capital of 12.3" in January 2022 and 7.8” in January 2024. There hasn't been a snowier than average February in the nation's capital since 2015 (9.8") or March since 2018 (4.5"). 

It's worth noting that March is the only month D.C.'s snowfall average has increased over the last decade (from 1.3" in 1981-2010 to 2.0" from 1991-2010). That's because March was D.C.'s snowiest month of the year four times between 2011 and 2020. 

The nation’s capital has had only one snowier than average December over the last decade (2017). Consequently, D.C.'s December snowfall average declined from 2.3" (1981-2010) to 1.7" (1991-2020). 

December used to be D.C.’s third snowiest month of the year, but has since been replaced by March. March has been the only month in the last decade that Washingtonians had above average snowfall with any regularity, with five such occurrences since 2011. Monthly snowfall can be a cyclical occurrence in the nation’s capital. For example, accumulating December snowfall occurred seven times between 2001 and 2010, but has only occurred five times since then. 

My colleagues and I on the WUSA9 weather team don’t see any accumulating snowfall on the horizon in the nation’s capital.

Meteorological winter gets underway

 

The sun has set on meteorological fall in the nation's capital

November 2024 finished 5.3° warmer than average in the nation’s capital and that made it the warmest on record. It was also a drier than average month which wasn’t good news for the ongoing drought conditions. Although no measurable snowfall occurred, some light snow and flurries was observed on November 22. That was the first time snow fell in the nation’s capital prior to Thanksgiving since 2018.

Meteorological winter officially began on December 1 and continues through the end of February. Average daily temperatures drop throughout December, according to NOAA. D.C.’s average high/low temperatures range from 53°/38° on December 1 to 44°/30° on December 31. D.C.’s warmest December temperature on record is 79° (December 7, 1998), while its coldest December temperature is -13° (December 31, 1880). Seven of the last 10 Decembers have been warmer than average in Washington, D.C.

The nation’s capital averages 3.41” of rain in December. Washingtonians can also expect an average of 1.7” of December snowfall (2.8” at Dulles Airport). However, nine of the last 10 Decembers have had below average snowfall, with 2017 being the lone exception. D.C.’s wettest December (7.56”) occurred in 1901 and driest (0.19”) in 1889. By comparison, the snowiest December occurred in 2009 with 16.6”. That was also the last time the nation’s capital had a white Christmas.

December’s weather can have wide fluctuations from one year to the next. The right ingredients need to come together only once to produce a large winter storm such as what happened in December 2009. 

NOAA’s Climate Prediction Center expects a weak episode of La Nina to develop this winter. That would help create conditions making near to below average snowfall more likely in the nation’s capital. Last winter produced just 8” of snow in D.C., well below the seasonal average of 13.7”. Washingtonians haven’t had a snowier than average winter since 2018-2019.

Nevertheless, D.C.’s cold start to December will continue for the entire week with temperatures more typical of January. Dry conditions will also continue for the next several days.

DC’s warm November comes to a cold end

 

A late-November day in the nation's capital

Despite the colder than average final two days of the month, November 2024 will still finish as the warmest on record in the nation’s capital. November will also finish as a drier than average month in the nation’s capital, the sixth such month of the year.

November had only five cooler than average days in the nation’s capital. That’s compared to 23 warmer than average November days. Three days even reached the 80s! That hasn’t happened since 1975. DC averages only one 80-degree November day roughly every five years, according to NOAA. Three record highs were also set this month.

With a monthly average temperature of 55.8° as of November 29 (that includes daily high and low temperatures), this month will finish over five degrees warmer than average. It will also set a new record for warmest November in the nation’s capital, breaking the existing record set in 2001.

Five of the last seven November’s were cooler than average in the nation’s capital, so this month should have felt especially warm by comparison. Ironically, while the recent trend has been for November to be cooler than average, eight of DC’s 15 warmest November’s have occurred just since 2000. NOAA’s current weather averages (for temperatures and precipitation) are updated every decade and the current averages reflect the 30-year period of 1991-2020. That means with the exception of 2022, those eight Novembers were factored into NOAA’s updated weather averages.

The fact that this November is drier than average has acerbated the drought conditions across the Mid-Atlantic Region. With only 1.81” of rain, well below the November average of 2.91”, this month is the 15^th with below average rainfall in the last 20 years. NOAA’s outlook for December is for near average temperatures with near to below average rainfall in the DC Metro Area.

DC’s Warmest Novembers (Source: National Weather Service)

1. 54.8° (2001)
2. 54.4° (1979, 1975)
3. 54.3° (2020, 1985)
4. 54.0° (1931)
5. 53.7° (2015)
6. 53.3° (1994)
7. 53.1° (2003, 1999)
8. 52.6° (2022, 2016)
9. 52.4° (2011)
10. 52.2° (2009, 1978)

Average – 49.9°