A ferocious sun glared down on the sixth annual Adams-Morgan Day yesterday, and the pavement was hot enough to bake a pupusa, but no matter. The record-breaking September heat may have made some summer-weary Washingtonians stay away, but those who did show up were undaunted by the 98-degree temperature.

Tens of thousands of people turned out to visit the 250 food stands and exhibits put up by the neighborhood's merchants along Columbia Road between 18th and 19th streets NW. Strollers took in an assortment of performances that ranged from a local restaurant's Mexican mariachi to the tap dance pyrotechnics of an elderly gentleman who goes by the name of "Mr. Rhythm."

Marion Barry, strolling down Columbia Road with his toddler son, Christopher, and a handful of reporters and assistants, stopped to buy a T-shirt from the AIDS Education Fund booth, then pointed to the range of stands that included exhibits of African jewelry, Jamaican food, antique American clothing and literature urging support for the Salvadoran rebels.

"Look at this diverse community," Barry said. "It's important to have neighborhood festivals like this, that stimulate community pride and bring together people from so many religious, ethnic and cultural backgrounds."

There are parts of Northeast Washington that have the stillness of a Southern backwater, and neighborhoods in Northwest that exhale the rarified air of prosperous middle-American suburbia. Not Adams-Morgan. It is perhaps one of the few areas of Washington where the excitement and diversity of a true world capital show through, and for out-of-towners, that was an essential part of the festival's charm. "There are so many kinds of food and crafts from all over," said Jeannine Ferguson, who just moved to the neighborhood from her native Oregon. "I've just tasted canolli a sweet cream-filled Italian pastry for the first time."

This year some members of the local Advisory Neighborhood Commission repeated charges made in previous years that the festival is the private domain of Harold Wheeler, chairman of the Adams-Morgan Day organizing committee and owner of the Columbia Station restaurant on Columbia Road which, like many restaurants along the street, traditionally does some of its best business during the festival.

Pat Patrick, director of the festival's organizing committee, disputed that assessment. "The largeness of the crowd mirrors the support the community has for Adams-Morgan day, and puts to rest the criticisms of a very small minority within the ANC," he said.

Yesterday's strollers--mostly white, and apparently for the most part residents of Northwest Washington--seemed to share Wheeler's view. "The food is good and street festivals are fun," said Connie Hershey, who lives within decibel range of one of the music stages set up at Columbia and Kalorama roads.

Latino vendors, who turned out in droves to sell charcoal-broiled meat and tamales and pupusas--spicy cornmeal pastries--were equally pragmatic. "The propaganda for the festival is all done in English, for Americans," said Gloria Melgar, from El Salvador. "Latinos know this isn't the Hispanic Festival held in July . But we come because we sell a lot."

Yesterday's heat shifted sales away from food and towards anything liquid. Some curious Anglos sampled Central America's typical tamarind, rice water and ginger drinks and, pronouncing them too sweet, headed for the beer. Craig Burk walked with two friends and three large sangrias through the crowd and expressed only one regret about the festival. "I wish it had been held tomorrow, because the weather is supposed to break,." he said.

For the legions who showed up in cut-offs, sandals, T-shirts or halter tops, the festival was a last sounding of summer. And thanks to the more than 30 performers at the five open-air stages, there was plenty of dancing in the streets. The Diversions, a post-punk local group, rocked hard and heavy for over an hour to enthusiastic bopping and loud applause.

Not everyone was a fan. "Listen to that music," a Colombian at a nearby booth complained. "Boom, boom, boom, it's all the same." For his taste, there were nostalgic ranchera songs at the Latino stage on Mintwood Place and jokes that provoked wry laughter from the community's recent immigrants.

"Our lead singer has disappeared for a little while," joked one of the members of the Mariachi La Plaza. "It seems he's having some trouble with the immigration authorities." Then he sang a song about a man who returns home after a long absence working across the border.