May 18, 2018
Heavy rain fell in southern Maryland during the night of May 17th into the morning hours of the 18th. 1-4 inches of rain caused flooding, including of streams. More moderate to heavy rain continued in that area on the 18th and 19th, prolonging some flooding in Saint Mary's County. Meanwhile, the cumulative effects of several days of rain throughout the region caused stream flooding, particularly on the Potomac River.
Source: NOAA National Weather Service Storm Events Database (event 758682). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Montgomery County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.