A little rain--even a lot of rain at times--wasn't enough to dampen the spirits of more than 35,000 people who gathered yesterday to witness this year's version of Washington's rite of spring, the 28th annual Cherry Blossom Festival Parade.

Despite the delicate pink lace of cherry blossoms in young bloom along the Constitution Avenue parade route, the irony of celebrating the coming of spring under a canopy of rain clouds was not missed. Just a few days earlier, Washingtonians were basking in the mildest temperatures of the year. Skies were clear and blue, breezes gentle and warm.

"Why couldn't they have had the parade yesterday," said Barbara Larkins of Coatesville, Pa., who came here to proudly watch her 9-year-old daughter, Carolyn, high step it down the avenue with the Young Americans Marching Unit.

She said she had been worried all day about the weather. Her biggest concern was that Carolyn's first chance to march in a parade would be rained out. They were both glad that didn't happen.

And so were the thousands who, despite the weather, packed their lunches and children and went off to claim a choice spot of turf to watch the more than 100 floats and bands that filled the avenue for more than two hours.

Dave Warwick followed the crowds with his Good Humor ice-cream cart. He wasn't much worried about the rain that was beginning to peck at his forehead. He said business couldn't be any worse than it was during last month's sunny St. Patrick's Day parade.

He said he was more bothered by Reaganomics than April showers.

But it was definitely the rain that bothered John Jones, who led his two children away from the promise of hours of brightly colored floats, painted-face clowns, and marching bands whose music is heard in the ears and felt in the tummy.

"It's just too bad out here," said Jones, whose rain-soaked sweatsuit was flapping in the harsh winds. His 4-year-old son and 5-year-old daughter struggled to hold their yellow umbrella against the wind.

"I'm going to take them over to McDonald's so they are not too fired up," he said as he led his youngsters away.

Almost bumping into the Jones family, Raymond Mercer was a few paces short of running down 10th Street NW, following the sound of the D.C. police motorcycle unit announcing the noontime start of the parade. Its street-rumbling roar sailed out over the distant chords of marching bands that kept little children on their feet.

Mercer calls himself a "parade fanatic." He said he has been addicted to marching band music since he was in the Army 32 years ago. Since then, he's tried to make all the area parades he could. He hasn't missed a Cherry Blossom Parade yet.

He walked in the rain from Lincoln Park to hear the music he says he loves so much. And could a downpour turn him back? "Under no circumstances," he answered in a shout, as the bands drew near.

Richard Goldsmith and his family appreciate new marching band music, too. Goldsmith, his wife Judy, and daughter Rachel applauded as the Lawrenceburg High School band from Lawrenceburg, Ind., went by, piping out a rousing rendition of "I'm Gonna Live Forever," from the movie "Fame."

"The spirit and enthusiasm and the quality of music is excellent," said Goldsmith, a market and publicity director for a Buffalo, N.Y., theater. "It's a beautiful parade."

He said the rain didn't spoil a thing.

Elizabeth Tucker of Baltimore might disagree. Tucker, 20, a member of the Cherry Blossom queen's court, never stopping waving and smiling as the rain assaulted her hair and white lace gown.

"I was kind of upset about it," she said, "but I hoped the parade was going to go on. It was a lot of fun, especially all the little kids on the sides." To the ancient strains of "Sakura," a traditional Japanese melody about cherry blossoms in the spring, 332 followers of the Nichiren Shoshu sect of Buddhism helped to heighten the parade's Oriental flavor. About 200 women dressed in pink and yellow kimonos carried handmade branches of satin cherry blossoms. The men, dressed in Japanese happi coats, followed the women in a brass band and drum corps.

Guy McCloskey, spokesman for the group, said most of the performers came from the Virginia and Carolinas areas. He said their participation yesterday was an "expression of our faith."