Is July DC’s wettest month?

 

U.S. Supreme Court, Washington, D.C.

NOAA’s (National Oceanic and Atmospheric Administration) current 30-year average temperature and precipitation totals for the United States reflect the period of 1991-2020. Since this period was appreciably warmer and wetter in the nation’s capital than the previous 30-year period of 1981-2010, there were significant changes. July saw the most significant changes in the updated data set.

Previously, July was DC’s third wettest month of the year with an average of 3.73” of rain. However, things changed dramatically with NOAA’s updated climate statistics that saw the decade of the 2010s replace the 1980s. July is now the wettest month of the year in the nation’s capital with a new monthly rainfall average of 4.33”. 

Here’s a look at recent rainy July’s in the DMV (DC, Maryland and Virginia).

2022: This July continued the recent trend in the nation’s capital for exceptionally wet days. A total of 4.05” fell on July 9, which was DC’s fifth wettest July day. To add to that, a daily rainfall record was set merely a week later on July 16 with another 1.38”. The combined rainfall of 5.43” on these two days accounted for nearly 75% of the monthly rainfall total of 7.61”.

2020: The monthly rainfall total of 6.51” was above average. What made this July significant was that 60% of the monthly rainfall occurred on just two days. A daily rainfall record of 2.04” occurred on July 7, while another 1.89” fell on July 23.  

2019: This July got off to wet start with measurable rainfall on five of its first eight days. The signature rainfall event was on July 8 when a daily rainfall record of 3.44” occurred at National Airport. That accounted for more than half of DC’s monthly total of 6.49”. Most of that rain fell in less than two hours, snarling the morning commute across the DMV.

2018:  An impressive total of 4” of rain fell at National Airport on July 21 that set a new daily rainfall record. Moreover, 8.52” of rain fell during the eight-day period from July 17 – July 24. It finished as the fourth wettest July in the nation’s capital with 9.73”.

2017:  This July finished with 9.15” of rain, making it DC’s wettest since 1969. During an eight-day period from July 22 – July 29, a total of 6.15” of rain fell that accounted for more than two-thirds of DC’s monthly total. The wettest day of the month was on July 28 when a daily rainfall record 3.31” was recorded at National Airport.