DC’s Rainy Year Continues

 

DC residents had another exceptionally rainy day on Wednesday when daily rainfall records were set at National, Dulles and BWI Airports.  With 2.02” of rain on Veteran’s Day at National Airport, it was the sixth day DC had at least 2” of rain so far this year.  Since January 1, 49.67” of rain fell in the Nation’s Capital.  That’s nearly 10” more than Washingtonians average during an entire year. 

Some have started to compare this year to 2018, which was DC’s rainiest on record.  Both years saw drier than average January’s and March’s, but a wetter than average February.  For the nine month period from April 1 – December 31, 2018, the Nation’s Capital had a rainfall surplus of 27.8”.  2018 also had a record 24 days with an inch or more of rain at National Airport.  By comparison, this year also had a significant rainfall surplus of 12.25” for the four-month period from July 1 – October 31.

The Nation’s Capital had 52.89” of rain during the first 10 months of 2018 and that would have been enough by itself to make 2018 one of its 10 wettest years on record.  However, the rain didn’t let up and November 2018 became DC’s wettest November on record and was followed by a very rainy December.  With 49.67” of rain so far this year, the Nation’s Capital needs only 2.92” during the rest of the year to put 2020 among DC’s Top 10 wettest years. 

The heavier rain events this year have also featured more rain from former tropical systems than in 2018.  For example, the nearly 3” of rain Washingtonians saw on August 3-4 was the result of former Hurricane Isaias.  Meanwhile, the remnants of Hurricane Zeta brought another 2.57” of rain on October 29-30.

Last year was also wetter than average in DC, but not unusually so.  Wetter and drier than average years are cyclical event.  For example, the wet period in the Nation’s Capital that began in 2018 followed DC’s driest two-year stretch (2016-2017) in 15 years.  Conversely, the dry 2001-2002 period in the Nation’s Capital was followed by DC’s third wettest year on record in 2003.

Washington, D.C.’s Ten Wettest Years (Source: NOAA)

1.  66.28” (2018)
2.  61.33” (1889)

3.  60.83” (2003)
4.  60.09” (1878)
5.  58.17” (1886)
6.  57.54” (1948)
7.  54.49” (1937)
8.  52.95” (1891)
9.  52.92” (1906)
10.  52.59” (1877)

 

Average: 39.74”