The End of Summer?

A Great Place to Cool Off, Great Falls, Virginia

Although we’re in the midst of a glorious three-day stretch of September-like weather, the end of meteorological summer doesn’t officially arrive until August 31.  This summer has been unique and can be broken up into two different periods.  From June 1 through July 4, there was a noticeable absence of extreme heat with only five days at or above 90 degrees.  Since July 5, the Nation’s Capital has had 40 of the last 49 days at or above 90 degrees.  

This very hot stretch of weather not only produced Washington, D.C.’s sixth warmest July on record, but also yielded the first triple-digit heat since 2012.  Part of July’s hot finish was DC’s longest stretch of consecutive days at or above 95 degrees (seven) since the record streak of 12 in 2012. August has featured an even more impressive stretch of hot weather.  Not only have there been multiple days of triple-digit heat in August for the first time since 2002, but rarer still were three consecutive days of triple-digit heat (August 13 – 15).  Prior to this month, the last time there were three consecutive August days at/above 100 degrees in Washington, D.C. was in 1930.

Part of what made the summers of 2010 to 2012 so hot across much of the eastern United States was the increased amount of urbanization.  That led to warmer overnight low temperatures and contributed to some of the warmest months on record in the Nation’s Capital.  This summer has tied the 2011 record (six) of number of days where low temperatures remained at or above 80 degrees. 

Through August 21, Washington, D.C.’s average high temperature this month was 92.7 degrees.  National Weather Service records indicate that’s above the August’s record average high temperature of 92 degrees from 1980.  However, the several days this week with high temperatures in the 80s will lower that number.  Nevertheless, this August remains poised to finish as one of the warmest on record in the Nation’s Capital and many eastern cities.

Washington, D.C. averages 36 days at or above 90 degrees in a given year and 2016 has already had 45 such days.  The record for most 90 degree days in a given year is 67 which occurred in 2010 and 1980.  My colleagues and I on the WUSA9 weather team expecting more 90 degree heat in the Nation’s Capital later in the week, so the August total of 17 such days will only grow.

Most August days at/above 90 degrees in Washington, D.C. (DCA – Source: NWS)

1.  22 (1980)
2.  21 (1943)
3.  20 (1988, 1983)
5.  19 (2002, 1995, 1966)
8.  18 (1900)
9.  17 (1968, 1872)  --> 2016 (Through August 21)