Summer breathed yet again on the Washington area for most of yesterday, but its warm, gentle breezes gave way before nightfall to torrents of rain and blustery winds that caused widespread flooding and property damage throughout the Wahington area.

The storms, which crashed into the area just as tens of thousand of commuters were beginning their struggle homeward, dropped nearly an inch of rain here in less than two hours, and almost three-quarters of an inch more over the next three.

Rain collected in intersections and underpasses and on sections of major commuter routes to depths of three to four feet in some places and traffic on the northbound span of the 14th Street bridge was backed up for several hours because of high water in the roadway.

Winds gusting up to 40 mph toppled tree limbs and downed power lines, but there were no reports of widespread power failures. In the most serious wind-caused incident, Prince George's County police reported that 13 privately owned single-engine airplanes parked at Hyde Field in Clinton were blown over, causing more than $75,000 damage.

Police said the gusts, which hit the airfield about 10 p.m., sent one of the small planes tumbling onto nearby Piscataway Road where its fuel tank ruptured, spilling high-octane gasoline onto the road. The craft was quickly righted, however, and returned to the air strip, police said.

National Weather Service officials were particularly concerned last night about heavy rainfall along the upper reaches of the Potomac, where nearly three inches was recorded last night and early today. Because the ground is unable to soak up so much rain in so little time, forecasters said they expect the Potomac to crest well above flood stage at Little Falls tonight. It was unclear early today, however, whether the crest would be high enough to cause serious flooding in areas along the river bank.

The day began pleasantly enough before it showed its true temper, as thousands of wool-clad bureaucrats labored damply in windowless offices rigged for winter, possibly wondering when this curious meteorological year would end.

The midafternoon siroccos came not off the Libyan desert, but off the Gulf Stream, southerly preludes to the passage of the cold front that brought last night's soggy blast from the Appalachians.

Yesterday's high of 68 was really not all that warm. True, it was 16 degrees over the Nov. 28 norm of 52, but a good six degrees under the record 74 set 11 years ago.

Watching the mercury was Charles Polinger who, as manager of the General Services Administration's heating operations and transportation district, is effectively the czar of climate in some 120 government buildings.

Normally, Polinger said, he's out of the chilled-air business by Oct. 15 and firing up boilers. This year, with a warm October, he kept the chillers on until Nov. 2 at the Department of Agriculture and the Forrestal complexes, then shut them down for yearly maintenance.

He wasn't ready to crank them back up for a one-day heat spell, he said yesterday, but could if the weather continued. Most buildings get by during short-term winter heat by opening a damper to let in outside air, humidity and all.

Buildings heavily impacted with computers, such as the Pentagon, do better. They stay air-conditioned year around, since computers are even more neurotic amid temperature shifts than people.

Meanwhile, as lunchgoers strolled in afternoon sunshine, the nation's chief weather forecaster faced a dozen television cameras and twice as many reporters yesterday in a muggy Commerce Department auditorium and predicted, with requisite aplomb, a warmer-than-usual winter for the entire eastern United States.

Donald L. Gilman, chief of the predictions branch for the National Weather Service, also forecast a colder-than-average winter for the western half of the country, with wetter-than-normal conditions from sea to shining sea.

It's the kind of combination -- warm in the east, cold in the west and wet all over -- that the nation hasn't seen since the 1974-75 winter, and before that in the late 1940s and early 1950s. It's also a combination that could presage serious storm activity in several parts of the country.

"Cold in the west, warm in the east -- that's a nice combination for storms," said Gilman, whose annual winter forecasts have become something of high theater while earning him a reputation as a kind of riverboat gambler among his forecasting peers.

Gilman, like any good gambler, hedged his bets with a significant number of "ifs" and couched all his predictions in terms of probabilities. He also declined to say specifically how much warmer is warmer-than-usual for the eastern half of the nation. But he added that it could be at least a fraction of a degree warmer and conceivably up to two degrees warmer, which "may not sound like much, but everybody will notice it."

The good news for the East comes after last year's winter of discontent, dominated by record cold and frost, beginning in late December. The last two weeks of 1983 "were so overpowering it sort of swayed the whole picture," Gilman said.

The forecaster, apparently hedging his own bet by wearing a sweater beneath his tweed jacket, acknowledged that he was off the mark in his last two forecasts. "The last two winters were actually below par for us," he said. "They were not adequate forecasts."

But overall, for the 25 years that the National Weather Service has been giving a winter forecast, the accuracy rate has been about 65 percent, he said.

The predictions for this year were based primarily on statistical data -- essentially looking at the weather for the last several seasons and from last winter, and making statistical calculations.

Unlike some other forecasters, Gilman ignores sunspots and dust clouds from volcanic eruptions as unreliable.

Gilman's predictions in some cases are the polar opposite of the forecasts found in the 1985 Old Farmer's Almanac.

The Almanac, relying on solar activity and its own "secret formula" dating to 1792, says, "winter in most sections east of the Rockies is expected to be colder and drier than normal, with below average total snowfall, despite relatively mild weather during much of November, December and March . . . . "

For west of the rockies, the Almanac predicts "generally below normal temperatures," and for the far West and Southwest "milder than normal temperatures."

But even the Almanac predicts milder-than-normal temperatures for this Washington D.C. area, which falls in the mid-Atlantic coast region, according to the Almanac's map.

The overall wetter conditions nationally could mean more snow in the Midwest, particularly Michigan and Ohio. But he cautioned that long-range forecasters almost never make a distinction between rain and snow.