June 2013: 4th wettest on record in Washington, D.C. and 4th warmest of 2000s

July 2, 2013

June 2013 delivered quite the deluge for many parts of the area as National Airport (DCA) reported its wettest month (9.97″) in over five years. Not since May 2008 dumped 10.66 inches has it been wetter.

It was also the first wetter-than-normal month since October of last year.   Compared to Junes dating back to the late 1800s, it was the fourth wettest on record and  6.19 inches above the 30-year normal.

Here is a chart showing how June 2013 compares to the other Junes of the 2000s along with the top ten ranking.  Notice that three years from the 2000s take up spots among the top 10 wettest years since the late 1800s now.

The graphic below shows how National’s precipitation was distributed through the course of the month and how the other airports fared.

The only daily rainfall record reported at any of three airports in June occurred on the 10th when 2.77 inches fell at National beating out 1945′s 2.27 inches for the same date (in case you are interested, 1945 also holds the record for wettest July with 11.06″).

June’s slightly warmer temperatures

Temperatures were definitely far less exciting with fewer extremes than what we experienced last year. This was the first June since 2009 that we did not hit 100F. The average temperature of 76.5F was 1.3F warmer than the thirty-year (1981-2010) climatology and the fourth warmest of the 2000s (21st warmest all-time) edging out last year by just 0.2F.  While slightly warmer than last year, we saw fewer extreme temperatures as you can see here on the daily tracking chart.  Also notice that warm (red) days out-performed cool (blue) days on the whole, but extreme temperatures were generally more rare.

Looking at June average temperatures through the 2000s reveals a general warming trend, but with certainly a fair degree of year-to-year variability.  We were about 4F cooler than the hottest June of the 2000s and 5F warmer than the coolest- almost right in the middle.

The wet weather and lack of any sustained severe heat waves can be attributed to a pattern that featured heat ridging (bump in the jet stream) out toward the Western U.S. and in the western Atlantic Ocean along with cool troughing (dip in the jet stream) in the Midwest.  We found ourselves in between that cool Midwest trough and the warm Bermuda ridge to the east.  This gave us plenty of back-and-forth variability as we saw, but nothing durable on the temperature front.

The frequent moist southerly flow between these two weather systems provided frequent heavy precipitation opportunities.  And this pattern affected all of the East Coast.

The National Weather Service posted a nice graphic yesterday listing all the East Coast impressive rainfall totals:

July 2013

Should we expect a June pattern repeat for July?  The start of the month is sure starting out that way with above normal precipitation right out the gate and near seasonal to warmer-than-normal temperature ranges.  The current pattern evolution would seem to argue another month that is 1-2F warmer than normal with above normal precipitation once again.  The National Weather Service is not offering us much of any significant guidance by favoring equal chances of wetter/drier/normal precipitation and warm/cool/normal temperatures as can be seen here.

For further information:

The National Weather Service publishes nice monthly assessments usually within a week of the close of each month (should be available shortly):

You can click on your closest airport location here:

Reagan National (DCA)

Dulles Airport (IAD)

Baltimore-Washington (BWI)

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Matt Rogers · July 2, 2013