The atmosphere was rain forest steamy, but the sounds were city cool at yesterday's third annual Charlin Jazz Society jazz picnic.

About 250 jazz fans helped turn the cramped social hall at Temple Sinai on Military Road into a lively mid-afternoon nightclub, while outside in a small garden volunteers sold hamburgers, kosher franks and beer to raise money for the music society.

Prominent local musicians, including Buck Hill, Clement Wells and Steve Novosel, also donated their services to the 4-year-old nonprofit organization, which sponsors concerts and runs a summer intern program for aspiring D.C. performers.

Linda Wernick, cofounder of the group, estimated the society would net more than $1,000 from the picnic, which, she said, "goes a small way toward helping us make Washington a better jazz city."

In addition to being a fundraiser, the Charlin celebration has become a yearly get-together for area musicians. Conversations yesterday drifted toward the joys and difficulties of performing music that attracts fanatic fans but yields few fortunes.

"D.C. is like every place else," said saxophonist Buck Hill. "You've got too many good musicians and not enough work. It's the story of our lives."

Clearly an audience favorite yesterday, Hill has recorded five albums and performs regularly in local nightclubs. He offered an observation to the many young performers in attendance: "It's a rough business, and you're not going to make a lot of money unless you're real lucky."

Lisa Rich, a singer who performed several Billie Holiday numbers with a snappy three-man backup group, was also hawking a new record and collecting names for a mailing list.

"This city can be really great for jazz, especially if the economy recovers some more and people come out," said Rich. "It's the closest thing to New York without having to be in New York. Look at the people here, sweating to death--those are real fans."

Antonio Brown, 15, came with a group of friends from the Charlin intern program, which exposes teen-agers to the business side of the music world. Dressed in a pink sweat suit and keeping time with the music on an imaginary set of bongos, Brown acknowledged the obstacles he'll face as a drummer, without abandoning any of his optimism.

"I'm getting together a soul group right now," said the Cardozo High School student. " . . . Eventually, I'd like to play the Capitol Centre, the Kennedy Center, you know, all over the world."

After a moment's reflection, he said he had no models as a drummer: "I make up everything myself. You could say I'm my own idol."

Like several of his friends, Brown named pop singer Michael Jackson as his favorite performer.

"He's the best as a dancer," said Angelina Alexander, 18, who hopes to be a singer.

Bill Law, a manager, came all the way from Charleston, W. Va., to showcase pianist Bob Thompson. "For us, this is a chance to crack the D.C. market and get to know some of the real veterans here," said Law while he waited for his man to take the stage.

"The city has a real international flavor with the people from all over the world," he said. "And we want to make it here, just like everyone else does."