Will there be a Thanksgiving Day surprise ?

 

A dry November day in Potomac, Maryland

Some may wonder why Thanksgiving falls on a different date every year. Federal law proclaimed it a national holiday to be celebrated on the fourth Thursday of November. That means Thanksgiving 2024 will occur on November 28 when D.C.’s average high/low temperatures are 54°/38°.   

D.C.’s warmest Thanksgiving occurred on November 22, 2007 with a record high temperature of 77°. By comparison, Washingtonians had an unusually cold Thanksgiving in 2018 when the high/low was only 42°/29° on November 22. 

Longtime Washingtonians may recall that it was 35 years ago when area residents last experienced a snowy Thanksgiving. That Thanksgiving, on November 23, 1989, had a two-day snow total of 3.5”. November 1989 finished 1.6° colder than average and was followed by DC’s coldest December since 1917. In fact, 1989 remains the only time Washingtonians had both a snowy Thanksgiving and a snowy Christmas.

Accumulating November snowfall in the nation’s capital has been exceedingly rare in recent years, with only one such occurrence since 2000. Daily snowfall records were set at all three D.C. Area airports on November 15, 2018. In fact, when NOAA updated its climate averages to reflect the 30-year period of 1991-2020, replacing the 1981-2010 data set, D.C.’s November snowfall average dropped from 0.5” to 0.1”.

This month got off to a very warm start in the nation’s capital with high temperatures in the 80s on three days for the first time since 1975. While no more record heat is expected, no unusually cold weather is expected either over the rest of November. This fall’s dry weather has also continued into this month with November poised to finish with below average rainfall. That will make this November the second in three years to be both warmer and drier than average in the nation’s capital.

Washington, D.C.’s Five Coldest Thanksgiving’s by High Temperature (Source: NOAA)

1.  30°: November 27, 1930
2.  33°: November 28, 1901
     33°: November 26, 1903
3.  35°: November 23, 1989
     35°: November 28, 1996

 

Washington, D.C.’s Five Warmest Thanksgiving’s by High Temperature (Source: NOAA)

1.  77°: November 22, 2007
2.  75°: November 22, 1979
     75°: November 20, 1941
3.  75°: November 30, 1933
     73°: November 24, 1927

Weather Quiz

 

A bright but cool day in the nation's capital

Prior to this month, when was the last time the nation’s capital had three November days with highs in the 80s ?

 

A. 2020

B. 2003

C. 1985

D. 1975

DC's record dry stretch comes to a close

 

A windy fall day in the nation's capital

DC’s record of 38 consecutive days without measurable rain came to an end on November 10 when 0.2” was observed. This fall has been exceptionally dry and the nation’s capital has a growing rainfall deficit that stands at 4.72”, as of September 1. This fall’s warmer and drier than average conditions have combined to produce widespread moderate to severe drought conditions across the Mid-Atlantic Region.

Although some showers are possible Thursday afternoon, no other rainfall is expected over the next week. There are some similarities between DC’s record 38 days without measurable rainfall, from October 3 – November 10, and the second and third longest stretches of dry weather.

The second longest period without measurable rainfall in the nation’s capital is 34 days from September 15 – October 18, 2007. Despite this dry stretch of weather, October 2007 still finished as DC’s 10^th wettest with 6.55” of rain. This was also DC’s warmest October on record, similar to how October 2024 finished 2.2° warmer than average. 

A strong episode of La Nina was in place during the 2007 – 2008 winter season. Consequently, a below average seasonal snowfall total of 4.9” occurred in the nation’s capital. La Nina winters in the United States often feature a more northerly storm track that can lead to drier winters and less snow for the Mid-Atlantic Region. La Nina conditions correlate to above average sea surface temperatures in the tropical Atlantic with below average temperatures in the eastern Pacific, near Central America.

The third longest period without measurable rainfall in the nation’s capital is 33 days from August 7 – September 8 in 1995. A wetter than average fall followed and a moderate-intensity La Nina occurred during the 1995 – 1996 winter season. It was an atypical La Nina winter in the nation’s capital with a seasonal snow total of 46”. Washingtonians experienced measurable snowfall in five consecutive months from November 1995 – March 1996.

NOAA expects a weak La Nina to develop for the upcoming winter season. That’s not good news for local winter weather enthusiasts. There have been 12 weak La Nina winter’s since the 1950s that produced a snowfall average of 9.4” in the nation’s capital. That’s below DC’s seasonal snowfall average of 13.7”. The most recent winter with weak La Nina conditions was the 2022 – 2023 season when DC had only 0.4” of snow.

That’s not to say the upcoming winter will be similar to past winters with La Nina conditions that followed long stretches of dry late-summer or fall weather. It merely illustrates the need to pay attention to your favorite meteorologists, such as those on the WUSA9 weather team, as the right ingredients need to come together only once to produce a memorable winter storm.