Rain fell for hours here yesterday, soaking pedestrians, inconveniencing motorists, canceling picnics and continuing an almost unbroken trend of weekend precipitation that has become a dominant factor in many aspects of Washington life.

In brief drizzles, sudden showers or drenching downpours, rain has fallen on at least one day of 19 of the past 23 weekends, intruding to various degrees on the way Washingtonians do nusiness, take their leisure and view the world around them.

"I Think people are just very tired of the rain," said the Rev. John Miller, rector of the Episcopal Church of the Holy Comforter in Vienna.

The weekend rain has been a hole in the pocketbook if you run a golf course, a burden if you operate a riding stable but a stroke of good fortune if you own an indoor tennis court.

It has been bad for bike rentals and for boat tours, and has been blamed by at least one clergyman for a decline in church attendance, but it has been good for the bookstore at the Smithsonian museum of History and Technology.

Not surprisingly, the precise degree of psychic weariness and economic adversity attributable to the constant weekend rain depends on individual welcome at a restaurant like the Old Angler's Inn, where a main attraction is dinning on an outdoor patio.

When weather prevents use of the patio, said restaurant manager Andre Condon, customers "stay home." On "a day like today," he added, with .84 inches of rain officially recorded by 5 p.m., "it's very slow."

Although rain has darkened almost every Washington weekend for the past three months, the total amount recorded here has been about 20 percent below average for the period - 7.88 inches as compared to an average of 9.87.

In Alexandria, bicycle rentals "have been pretty bad on weekends" at the Bicycle Rack, which both rents and sells.

Owner Thomas Early explains the problem simply: "If the weather is good," he said, "people come out. If it is not good," he added, "they stay home."

During yesterday's rain, he rented "two or three" bicycles to riders who "got very wet."

But while people were leaving the bicycle paths, they were coming to the Alexandria Library on Queen Street in large numbers - library officials reported a "tremendous crow" there yesterday.

And at the Smithsonian's Musemum of History and Technology, bookstore manager Will Farnam figured that the rain "probably helps us."

Rather than deter tourists from visiting the mall, Farnam said, rain sends them into the museums for longer periods of time than usual. That leads to more people visiting the store, he said, adding "I think that people who come in the store will buy books."

It was busy as well at the Reston Racquet Club. "When it's raining," said Sue Karich, who was at the desk. "it really picks up in here . . ."

Rain was not welcome, however, at the Brandywine riding stable in Brandywine, according to owner Pamela Hardin.

It doesn't "affect" the stable's business, Hardin said, "it kills it."

Good weekend business is essential to the sucess of the stable, Hardin said, adding that this year's string of rainy weekends has made 1979 a "very" tough year.

At the First Baptist Church, Georgetown, rain has had "a deleterious effect on attendance," according to the pastor, the Rev. W.D. Abrams. "We've had so much of it on many Sundays," he said.

Peggy Bordeaux, a clerk at Washington Boat Lines said the river tours that leave from the docks at Georgetown and near the Lincoln Memorial have been "really hurt," by the rain, but she could not give figures.

A man who could give figures was Kerry Payne, assistant manager of the golf course in East Potomac Park. To him the rain has meant 10,000 rounds of golf unplayed and more that $30,000 in revenue lost in the past three months. "This weather's really pretty down on us," he said.

One area merchant, who did not wish to be named, contended that rainy weekends, by limiting available activities, boost store sales.

But Roi Wilson, manager of the Morton's store at 12th and F streets NW described business yesterday as "less than normal," and said the rain has kept customers away.

At the J.C. Penney's store on Wilson Boulevard in Arlington, senior merchandising manager Mattie Hunter termed business "slow."

Over the months, she noted the effects of rainy weekends have varied, with customers proving more likely to ignore the elements on a Saturday than on a Sunday.

If there were those who gained from the rain and those who lost, there were also those for whom it didnt make much difference.

At the zoo, overall weekend attendance has remained normal despite the rain, according to zoo police Sgt. James D. Jackson.

Much of the weekends rain has been in the form of brief showers, he said. When skies have cleared the crowds have come back.