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.  

A closer look at some November hurricanes

 

Hurricane Paloma, 2008 (Source: NOAA)

November is the final month of the Atlantic hurricane season when major hurricanes are increasingly rare compared with earlier in the season. However, earlier this month Rafael became the Atlantic’s first major November hurricane since 2020. A “major” hurricane is defined as a Category 3 or greater storm on the Saffir-Simpson Hurricane Wind Scale with sustained winds of at least 111 mph.

Rafael (2024): A late-season storm, Rafael became a major hurricane on November 6 shortly before making landfall in Cuba as a Category 3 storm. Its peak sustained winds reached 120 mph with a minimum central air pressure of 956 millibars (mb). By comparison, standard sea level air pressure is approximately 1013 mb. Although Rafael is weakening and will not make landfall in the United States, it did briefly regain major hurricane status in the Gulf of Mexico.

Iota (2020): Less than two weeks after Eta became a Category 4 Atlantic hurricane, Iota was an even stronger storm. At peak strength in the Caribbean Sea, Iota nearly reached Category 5 intensity with sustained winds of 155 mph and a minimum central air pressure of 917 mb. Iota caused widespread damage in Central America, not far from where Eta made landfall. 

Paloma (2008): Hurricane Paloma formed in the Caribbean Sea and reached peak intensity on November 8 as a Category 4 hurricane with sustained winds of 145 mph and a minimum central air pressure of 944 mb. Paloma was also significant because it marked the first known instance when major hurricanes formed in the Atlantic Ocean Basin (that includes the Gulf of Mexico and Caribbean Sea) in five consecutive months (July through November).  

Kate (1985): Kate reached peak intensity as a Category 3 storm in the Gulf of Mexico on November 20 with sustained winds of 120 mph and a minimum central air pressure of 953 mb. Kate weakened slightly to Category 2 status before its November 21 landfall on the Florida panhandle. That made it the latest landfalling hurricane on record in the contiguous United States. Kate was also the fourth hurricane to impact the U.S. Gulf Coast during the 1985 season and did an estimated $300 million in damages (unadjusted for inflation), according to NOAA.

Cuba Hurricane of 1932: The strongest November hurricane occurred so long ago that it was before hurricanes were named. Consequently, it’s referred to as the “1932 Cuba hurricane” and remains the Atlantic’s only Category 5 November hurricane on record. It reached peak intensity on November 6, 1932, with maximum sustained winds of approximately 175 mph and a minimum central air pressure of 915 mb. The devastating storm made landfall as a Category 4 hurricane in Cuba on November 9. 

Since hurricane hunter flights didn’t begin until the early 1940s, the most accurate way to measure the intensity of an offshore tropical storm or hurricane was by ships at sea.  Since these measurements weren’t made at the center of the storm, the air pressure could have been even lower.

 

DC's early November warmth

An early November day in suburban Washington, D.C.

The nation’s capital has averaged one 80-degree November day roughly every five years dating back to the mid-1990s. Washingtonians already had one 80-degree day on November 1, when the high was 83°. That’s what makes today’s highs near 80° and tomorrow’s highs in the low 80s all the more unusual for the nation’s capital.

Although the nation’s capital had an 80-degree November temperature as recently as 2022 prior to last Friday, there haven’t been two 80-degree November days since 2003. Five of the last seven November’s have also been cooler than average in the nation’s capital so any 80-degree warmth this late in the season has felt especially warm.

While the recent trend has been for November to be a cooler than average month in the nation’s capital, 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, all eight of DC’s very warm November’s since 2000 were taken into account in NOAA’s updated statistics. Some of that can be attributed to the urban heat island effect, but the overall trend has been for warmer than average temperatures compared to NOAA’s previous 30-year period of 1981-2010.

A warmer and drier than average November doesn’t correlate to a warmer and drier than average winter the same way a colder and wetter than average November doesn’t foreshadow a snowier than average winter. This fall has been warmer and drier than average in the nation’s capital and NOAA’s November outlook is for more of the same.

Not only are more above average temperatures in store for the nation’s capital this week, but drier than average conditions will also continue as my colleagues and I on the WUSA9 Weather Team aren’t expecting any beneficial rainfall over the next 7 – 10 days. 

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)
11. 52.0° (1990)
12. 51.8° (1982, 1977, 1946)

DC’s dry start to November

 

October 2024 finished as a warmer and drier than average month in the nation’s capital for a second consecutive year. The nation’s capital experienced its warmest Halloween since 1950 with a high temperature of 83°. Last month’s 1.48” of rain at National Airport is notable for occurring entirely on the first two days of the month.

October’s warm conclusion continued on November 1 with a high of 83° in the nation’s capital.  However, cooler, more seasonal weather has arrived this weekend with highs closer to average in the 60s. Normally, D.C. residents see falling temperatures throughout the month with average daily/high low temperatures ranging from 64°/46° on November 1 to 53°/38° on November 30, according to NOAA. 

D.C.’s warmest November temperature on record of 86° occurred on November 1, 1974. Meanwhile, D.C.’s coldest November temperature of 11° was on November 30, 1929. Five of the last seven November’s have been cooler than average in the nation’s capital. However, November’s outlook from NOAA’s Climate Prediction Center is for above average temperatures and near to below average rainfall in the D.C. Metro Area.

D.C. residents have seen a fair amount of dry November weather over the last 20 years. There were two notable exceptions with November 2018 that finished as D.C.’s wettest on record with 7.57”. November 2020 also finished as D.C.’s sixth wettest (6.14”). November rainfall average in Washington, D.C. is 2.91”, according to NOAA.

Longtime Washingtonians may recall the record-setting Veteran’s Day 1987 snowfall when 11.5” accumulated. That remains D.C.’s largest November snowfall on record. There has only been one instance of accumulating November snowfall in the nation’s capital over the last two decades. A daily snowfall record of 1.4” occurred at National Airport on November 15, 2018. Although the 2018-2019 winter season was the last to be snowier than average in the nation’s capital, November snowfall isn’t a reliable predictor of what the upcoming winter season will be like.

Since there’s been so little November snowfall in recent years, NOAA’s average November snowfall total for Washington, D.C. decreased from 0.5” to 0.1” in 2021 when the climate averages were updated.