Washington's string of three consecutive 90-degree days ended yesterday, but with a high temperature of 89, it seemed that only the thermometer could tell.

It was hot enough in Arlington yesterday to close two schools early and send 1,900 students home. The schools were Wakefield Senior High and Williamsburg Intermediate.

At the federal courthouse in Washington, where the air conditioning chose an inopportune time to malfunction, it was hot enough for U.S. District Judge Stanley Sporkin to permit lawyers to appear before him in shirt sleeves.

And on Capitol Hill, where electricity was cut off to about 900 homes and businesses by a power failure described as unrelated to the weather, Fourth Street SE resident Mark Wigmore said it was "dark and hot."

Although the mercury at National Airport failed to rise above the 89 degrees recorded at 12:45 p.m., warmer temperatures were measured elsewhere in the region, helping to validate the sense of midsummer oppressiveness given by the unseasonable heat.

Dulles posted a 90. In downtown Baltimore it was 92. Baltimore-Washington International Airport set a record with a 93 reading at 1:45 p.m. (The old record was 92, set only last year.)

In Washington, high thin clouds, spun off by thunderstorms developing to the west, filtered out enough of the fierce June sunlight to keep the city from recording a fourth consecutive 90-degree day.

Small amounts of rain fell in spots around the city last night, but showers were much heavier in the afternoon at Rixeyville, Va., (2.75 inches), Cumberland, Md., (1.49 inches), and Big Meadows, Va., (1.2 inches), according to National Weather Service forecaster Bob Oszajca.

He said that high temperatures should be near 90 today and tomorrow but that a cool front should arrive Thursday.