A tornado watch is in effect for the Baltimore-Washington area, including Montgomery County, until 10 p.m. Monday.
The watch, issued by the National Weather Service Monday afternoon, covers 21 counties, Baltimore city and Washington, DC.
NWS issues a "watch" when the risk of a tornado has increased "significantly," but none has been sighted.
A flash flood watch is also in effect for much of the Baltimore and Washington area through Monday evening.
A flood warning is in effect for Senenca Creek at Dawsonville, near Darnestown, affecting portions of Montgomery County.
Heavy rain is in the forecast for the Monday evening, with a chance of showers after midnight, according to the National Weather Service forecast.