Nearing Record Territory

Although Washingtonians haven’t had any record heat this month, every day this July has been warmer than average.  Yesterday was day 21 of 90° heat out of the first 22 days of July.  DC’s record for most 90° days during of July is 25, which occurred in 2011.

Washingtonians have seen 90° heat on 26 of the last 27 days.  That includes DC’s third longest heat wave on record of 20 days (June 26 – July 15).  A “heat wave” is defined as three or more consecutive days with highs of at least 90°.  Most of those days featured highs in the low to mid-90s.  My birthday, July 16, has been DC’s only day so far this month with a high temperature of less than 90°.

A new heat wave began July 17 when the high temperature was 96°.  In fact, for the five-day stretch from July 17 through July 21, DC had its longest stretch of consecutive days with highs of at least 95° since 2016.  NOAA’s Climate Prediction Center is forecasting above average temperatures to continue in the Mid-Atlantic Region over the final eight days of July.  My colleagues and I on the WUSA9 Weather team are forecasting many 90° days over the next week. 

Consequently, July 2020 is all but certain to eclipse the 2011 record for most 90° July days.  Making that even more remarkable is the fact no triple-digit heat has occurred this month.  Although 100° heat is often harder to occur at National Airport compared to downtown given its proximity to the Potomac River, DC residents have seen plenty of it in the last decade.  A total of 17 days of triple-digit heat occurred in the Nation’s Capital between 2010 and 2012.

What July 2020’s heat has lacked in overall intensity, it’s made up for in consistency.  Today will be day 22 of 90° heat so far this month in Washington, D.C.  That will tie July 2020 for sixth highest total.  The fact that July 2020 has been so much warmer than average without any 100° is ironic.  The last time Washingtonians experienced triple-digit heat was August 15, 2016.

DC’s Warmest July’s By Average Temperature (Source: NOAA)

1.  84.5° (2011)
2.  84.0° (2012)
3.  83.1° (2010, 1993)
5.  83.0° (1999)
6.  82.7° (2016)
7.  82.6° (1987)
8.  82.3° (1980)
9.  82.1° (2019, 1955)

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DC’s Most 90° July Days (Source: NOAA)

1.  25 (2011)
2.  24 (1993, 1987)
4.  23 (2016, 1988)
6.  22 (2019, 2012, 1999, 1994)
10.  21 (2010, 1980, 1878, 1872)