While the “dog days” of summer continue well into August by most definitions, temperatures are on the decline with the year’s hottest month of July largely behind us. Sure, these cool facts might not always be apparent every single day, but by August’s end the idea that refreshing times are ahead is often starting to become noticeable.
From July to August we see the monthly average temperature drop 1.7 degrees, from 79.8 degrees to 78.1. This is calculated off of the current (1981-2010) temperature normals for Washington. The normal high is 88.4 degrees for July and 86.5 degrees for August. The decline from summer’s peak heat is slower than the increase from June into July, and August ranks as D.C.’s second hottest month of the year.
Individual daily high temperature normals peak from July 11 through 17 at an unrounded 88.7 degrees. Normal lows hit their warmest stretch a few days later, and hold at 71.4 degrees from July 15 through 23. The climatological hottest days of the year are July 15 through 17, when the normal average overall temperature is 80.1 degrees. Comparatively, July 1 has a normal overall temperature of 79 degrees while August 31 is 76 degrees.
When it comes to the often-used 90-degree day metric, August again falls short of July, at least on average. August’s average of 10 days with 90 degree or higher heat might still be too much to bear, but the respite from July’s 14 days at that level is welcomed. By the time August closes, only about 8 percent of D.C.’s normal warm-season 90s are still ahead. Sometimes there are no more.
It’s worth noting that eight of 22 Augusts since 1990 have been warmer than the July preceding. Yet, all but two of those years featured cooler than normal Julys, and the other two were pretty close to normal. That’s something we were not so fortunate to have happen this year as we stare down what appears to be the second warmest July on record.