A hot day in Washington, Aug. 20. (Carol Jean Stalun via Flickr)

With three 100-degree days and a record number of 90-degree days, August in Washington finished as the second hottest on record. It very nearly tied August 1980 as the hottest, falling short by just a tenth of a degree.

The almost record-hot August helped push the area’s meteorological summer (June-August) average temperature to the third hottest in recorded history (which dates to 1872):

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Hot days in August came early and often. Seventy-five percent of the days reported high temperatures of 90 degrees or higher — for a total of 23, the most on record (passing 1980’s 22).

In a rare feat, August’s average temperature of 82.7 exactly matched July, which is normally the city’s hottest month. (The last time August was hotter than July was almost a decade ago, in 2007.) July and August together had a total of 46 90-degree days, the most on record (breaking the mark of 43 days from 1988).

Since 2000, Washington has had 40 percent of its hottest 10 Augusts and 60 percent of its hottest 10 summers.

Amazingly, five of the top seven hottest summers on record in Washington have all occurred since 2010.

The unusually hot August and summer fits in with a long-term summer warming trend, which is expected to continue as greenhouse gases from human activity accumulate in the atmosphere and areas around the airports urbanize.

Other parts of the region were also abnormally warm during the month.

Washington Dulles International Airport had its hottest August on record, beating 2007 by 0.8 degrees (records date to 1963).

At 79.1 degrees, Baltimore fell short of its hottest August by about 1 degree (80.3 in 1900, when measurements were taken in downtown Baltimore, rather than Baltimore-Washington International Marshall Airport).

Robert Leffler, a cooperative weather observer, said the average August temperature at his weather station in Damascus, Md., tied for the third hottest on record since he began taking measurements 43 years ago.

Extreme temperatures during August

In terms of monthly extremes, Washington hit 101 to outdo July’s hottest reading of 100. Our “coolest” temperatures were briefly in the upper 60s just last week.


The hottest weather concentrated in the middle of August, which managed three straight 100-degree readings in the city.

Here is the list of all the records in Washington, Dulles and Baltimore during the month:

D.C.

  • Aug. 12: Record high of 99 ties 1926 and 1900.
  • Aug. 13: Record high of 101 ties record from 1881.
  • Aug. 14: Record high of 100 ties record from 1943.
  • Aug. 14: Record warm low of 80 ties 2002.
  • Aug. 15: Record 1.16 inches of rain, beating 1941’s 1.15 inches
  • Aug. 26: Record warm low of 77 ties record from 1993.

Dulles

  • Aug. 7: Record warm low of 74 degrees, beats 72 in  2012, 2011 and 2007.
  • Aug. 10: Record warm low of 75 tied 2001.
  • Aug. 11: Record warm low of 75 tied 1988.
  • Aug. 12: Record warm low of 77
  • Aug. 13: Record high of 99 beats 98 in  2002
  • Aug. 13: Record warm low of 78 beating 76 from 1988.
  • Aug. 14: Record warm low of 76 beats 75 from 2005, 2002, and 1988.
  • Aug. 26: Record high of 95 tied 1998, 1993, and 1975.

BWI

  • Aug. 12: Record warm low of 79 breaks the record of 78 from 1926.
  • Aug. 15:  Record 1.64 inches of rain beating 1934’s 1.4 inches.

Rainfall

D.C. logged 2.79 inches of rain in August, which is about 0.14 inches below normal. This made it the 59th driest of all time or 88th wettest — if you prefer. The summer total of 9.6 inches marked he fifth driest of the 2000s, but only 0.84 inches below the 30-year normal, which is not abnormally dry.

Prevailing pattern

The Eastern United States roasted in August, with several cities expected to finalize their hottest or near-hottest readings on record. This follows the pattern of other recent summers with developing La Niñas (like 2010, 2007 and 2005). The jet stream frequently dipped a little bit in the Western United States and then surged north into the Eastern United States to keep us under a dome of hot high pressure.