Ranking July 2017

U.S. Capital, Washington, D.C.   Source: National Park Service

To paraphrase, Charles Dickens, the legendary author this month has been a tale of two seasons in Washington, D.C.  The first three and a half weeks of July ranked among the hottest on record in the Nation’s Capital.  However, there has been a dramatic shift in the weather pattern across the Mid-Atlantic Region over the last week.  That’s helped produce one of the wettest Julys on record for Washingtonians with some fall-like temperatures.

Through July 29, Washington, D.C. has a total of 9.15” of rainfall at National Airport.  That makes this the seventh wettest July on record since 1871, and the third wettest since 1941 (the year National Airport opened).  That’s largely due to the 3.78” that’s fallen just since Friday.  Washington, D.C. averages 3.73” of rain during the entire month of July.  

What’s more, Friday, July 28 was the first time that more than 3” of rain fell in a single day (3.31”) in the Nation’s Capital since October 29, 2012 (3.85”).  The significantly wetter than average weather this month has gone a large way toward mitigating the ongoing rainfall deficit.  Dating back to August 1, 2015, Washington, D.C.’s rainfall deficit on June 30, 2017 stood at 14.84”, but that number has since fallen to 9.18”.

The rainy final week of the month also had a big influence on temperatures.  On July 25, Washington, D.C’s average temperature (combining daily high and low temperatures) was 83.3° (3.5° warmer than average).  That was largely because 19 of the first 24 days of the month had high temperatures of at least 90°.  The high temperatures at National Airport on July 28 and 29, respectively, were 81° and 77°, more characteristic of mid-to-late September than July.

Consequently, this month’s average temperature has fallen to 82.1°.  Eight of the last ten July’s have been warmer than average (79.8°) in the Nation’s Capital.  With 9.15” of rain this month, July 2017 has also been DC’s wettest month in more than two years since June 2015 (11.94”).  NOAA’s outlook for August in the Mid-Atlantic Region is for warmer than average temperatures and near average precipitation.

Washington, D.C.’s Wettest July's  Source: NOAA

1.  11.06” (1945)

2.  10.63” (1886)

3.  9.95” (1905)

4.  9.59” (1922)

5.  9.44” (1969)

6.  9.41” (1917)

7.  9.15” (2017)

8.  8.40” (1891)

9.  8.37” (1878)

10.  8.13” (1889)