The vengeful remnants of the dog days of August, which have roasted the metropolitan area in 90-degree temperatures for a week, continued to force school closings in Maryland and Virginia yesterday, but were punctuated by early-evening cloudbursts that pelted parts of the area with about an inch of rain during the rush hour and caused scattered power outages.

National Weather Service forecaster Bob Oszajca said the high yesterday was 95, three degrees below the record set on Sept. 9, 1872, but well above the date's normal high of 82 degrees The last seven consecutive days of 90-degree temperatures ties the longest siege of such temperatures recorded in the area in any September since 1884.

But Oszajca said last night's rain would usher in little relief today, with highs still expected in the 90s and a 30 percent chance of rain. Temperatures are not expected to taper off into the low to mid-80s until tomorrow, when a cool high pressure system is expected to move into the area, he said.

Yesterday's torrid temperatures forced school officials in Prince George's, Prince William and Arlington counties to send students home early, as they have several times in the last week.

At Howard University about 150 dental school students staged a noontime demonstration after they were forced to cancel appointments with patients when school officials closed their building because of lack of air conditioning.

In the midst of the evening rush hour, a line of thunderstorms drenched parts of the Washington area. Smaller amounts of rain were recorded in southern Montgomery County and southern Fairfax County and the District. "We also got some reports of half-inch sized hail in Bowie," Oszajca said.

In Northern Virginia, where power company officials have been logging near-record power usage as a result of the stubborn heat wave, spokesman Jim Buck said nearly 3,600 customers were without electrical service for about an hour in Reston and Herndon area.

"The heat has given us much problem, but the thunderstorms have brought some problems with lightning . . . . We don't expect homes in Sterling Park to be back in service for the next few hours," Buck said.

In the District, PEPCO spokeswoman Nancy Moses said high winds knocked trees into overhead power lines, interrupting service to about 3,700 customers in parts of the District, College Park, Cheverly, Rockville, Gaithersburg and Kensington. "There is no estimate as to when power will be back on, I just hope most of it will be restored before the Redskins game comes on," Moses said.

Montgomery County fire officials reported two houses in Rockville were damaged by fires after being struck by lightning during the thunderstorm. At one of the houses, in the 12600 block of St. James Road, damage was estimated at $45,000. At the other, on Lowery Court, authorities said damage amounted to about $8,000.

Rainfall amounts during the cloudbursts varied widely from place to place within a relatively small area. In Bowie, according to the weather service, precipitation was measured at .97 inches, and at Dulles Airport, the figure was .83 inches. At National Airport, the city's official measuring station, only .13 inches of rain was measured.

In downtown Washington,where the storm arrived around 5 p.m. just as many people were leaving work, the rain was hard but relatively brief. Skipping around sidewalk puddles and over curbside streams, briefcase-wielding pedestrians dashed for buses and subway entrances, clutching windblown hats and umbrellas.