It is still a dry year, but recent showers have had an effect. At Reagan National Airport, where official measurements are made for Washington, it has not been a dry month.
As of 5 p.m. Saturday, August rainfall at the airport was slightly above normal for that point in the month. The normal amount of rainfall through Aug. 25 is 2.4 inches. The amount that had fallen as of that hour was 2.46 inches.
It was not much above the normal figure — only six hundredths of an inch — but it was notable for a year such as this. Precipitation in Washington has not only been below normal for the year, but it has also been below normal for every month through July.
This month’s totals have been enhanced by two days of substantial moisture, Aug. 10 and Aug. 21, each of which delivered 0.59 inch of rain to National Airport’s gauges. The Aug. 21 rain pushed the month out of a substantial rain deficit. At the close of Aug. 21, precipitation for the month amounted to 2.06 inches, just above the 2.04 inches that is normal.
Since then, enough rain, including Saturday’s 0.05 inch, has fallen to keep the totals for August above normal. Another half-inch or so of rain is needed by the end of the month if August is to snap the string of seven consecutive months with below-normal precipitation.
For the year, Washington precipitation remains well below normal. The total — 18.39 inches as measured at the airport — is about 29 percent less than normal. That is not nearly as dry as in some parts of the country, but it is still a substantial deficit.
Summer rains are often produced by thunderstorms of limited area that can bring significantly different amounts of precipitation to places that are not far apart. That helps explain why August rainfall at Dulles International Airport remained below normal Saturday, along with the yearly figure.