DC’s Wet 2018 Continues

September 2018 got off to a wetter than average start in the Nation’s Capital even before the remnants of Florence impacted the DC Metro Area.  A total of 47.35” of rain has occurred in the Nation’s Capital since January 1.  That’s the third highest total for the time period in Washington, D.C., according to the National Weather Service.  Washington, D.C. averages 39.74” of rain (including liquid snow-equivalent) for the entire year.  

DC had such a wet spring and summer that it’s easy to forget that 2018 got off to a drier than average start.  January 2018 and March 2018 were a combined 3.43” drier than average.  Ordinarily having two drier than average months over a three-month period isn’t that unusual.  However, it is significant when you consider that 23 of the 29 months (prior to January 2018) were also drier than average in the Nation’s Capital.

There has been a huge turnaround in the overall weather pattern since the end of March.  Washingtonians have now had six consecutive wetter than average months since then.  Prior to the current streak, Washington, D.C. hasn’t had six or more consecutive wetter than average months since 2003.  There have been a total of 17 days with at least an inch of rain in Washington, D.C. through September 20, for the second highest such total on record behind 1886 (19).

DC’s wettest month of the year was July with 9.73” of rain.  That eclipsed the 9.15” of rain which occurred at National Airport in July 2017.  This is the first time that more than 9” of rain fell in consecutive July’s in the Nation’s Capital since weather records began in 1871.  Making these rainfall totals even more significant is that neither July featured any rainfall from a decaying tropical system.  One of DC’s wettest days on record occurred on July 21 when 4” of rain fell at National Airport.  That was DC’s highest daily rainfall total since September 30, 2010 (4.66”).  

If Washington, D.C. were to see merely average rainfall during the final three months of 2018 then the Nation’s Capital would finish with an annual total of 56.97”.  That would make 2018 DC’s fifth wettest year on record and wettest since 2003 (60.83”).

NOAA’s most recent three-month precipitation outlook is for above average precipitation for the Mid-Atlantic Region.  Assuming that holds true, then DC Area residents can expect wetter than average conditions to continue and for 2018 to finish as one of the wettest years on record.