Washington area residents - who have awakened at night by booms and flashes of light, and caught without umbrellas during the day - can expect more of the same through the weekend, the National Weather Service said yesterday.

A lazy stationary front on the Virginia-North Carolina border, sandwiched by cool winds from the north and tropical winds from the Atlantic, is responsible for all the thunderstorms and for the 1 1/2 inches of rain that the area has had since Sunday.

Yesterday's rainfall of .15 inch and high temperature of 84 degrees, recorded at 4 p.m., will be closely matched today, according to the Weather Service. The service predicts mostly cloudy, warm and humid weather today through Friday, with high temperatures between 82 and 85 degrees, and a 50 percent chance of thunderstorms and rain.

The service said the stationary front to the south will remain idle through the weekend, causing variable weather and intermittent thunderstorms through Sunday.

Inland portions of Virginia and the Chesapeake Bay area appeared to be hit the hardest by yesterday's stormy weather. The weather service issued a marine warning for the bay area after a waterspout was sighted near the mouth of the Potomac River.

Minor flooding and heavy rain was reported in Norfolk and Richmond, while four inches of rain yesterday in the Springfield area caused some flooding on Fairfax County roads.

If it is any consolation, James Wagner, a long-range forecaster for the weather service, expects this year's August weather to be much more bearable than August 1977 when muggy, above 90-degree weather stretched through two weeks.