U.S. Drought Monitor in Virginia and Maryland as of July 31, 2012. (U.S. Drought Monitor)

Related: Drought intensifies in most-parched areas of U.S.

The string of 7 straight dry months - while unprecendented to kick off the calendar year - has been matched or exceeded on at least 9 occasions within a given year or overlapping two years. The most consecutive months with a rainfall deficit in Washington, D.C. is 10, occurring in both 1896-1897 and 1930-1931.

The latest U.S. Drought Monitor classifies a large part of northern Virginia in moderate drought while south of Baltimore, much of Maryland is in moderate to severe drought.

In Maryland, the fraction of the state in severe drought grew from 20 percent to 29 percent in the last week due to mounting precipitation deficits east of the Chesapeake Bay.

From central Virginia to the Mason Dixon line, the only area not classified as at least moderately dry is northern Maryland, adjacent to the Pennsylvania border.

The Drought Monitor also indicates D.C. proper is in moderate drought. However, sections of the city received appreciable rain in localized downpours in July - resulting in rainfall totals greater than regional averages.

Related: 2nd hottest July on record in Washington, D.C.; warmest year-to-date on record, 5th driest

Ian Livingston contributed to this report.