Now that summer is upon us, you don't have to wait till the sun goes down to hear a live concert or see a dance performance in Washington. Showtime is noon - at parks, churches and theaters from Capitol Hill to Dupont Circle - and in some cases, admission is free.

Washington is a city of office workers, and most of the midday entertainment is downtown or on Capitol Hill, where the concentration of office buildings is highest. While there are noontime shows year-round, gears shift during the spring, and many of the players take to the streets.

When the show moves outdoors, chamber playing gives way to a hardier type of music that can compete with buses and picnickers. Like the music of the Hine Junior High School Band, which will be performing today in front of the National Portrait gallery, on F Street NW between 7th and 9th, as part of the Streets for people program.

Streets for people started this week and will continue every Tuesday and Thursday throughout the summer between 11:30 a.m. and 1:30 p.m. when it's not raining. The D.C. Department of Recreation, which sponsors the concerts, estimates that on some days last summer, as many as 1,500 people came by on their lunch break.

Streets for People serves the dual purpose of making downtown a more interesting place to work and shop and giving local performers more exposure. A few of the groups lined up for this summer are the D.C. Youth Ensemble, the D.C. Community Orchestra, the marionettes of the D.C. Recreation Caravan, the stage bands of Dunbar and McKinley Senior High Schools and others, such as the Ambassadors and the Trinidad Steel Band.

Starting July 1 and continuing through August, there will be music in three other downtown parks, also sponsored by the Recreation Department with contributions from local businesses. Bluegrass, folk, folk, rock, jazz and dance group will play Rawlings Park (19th and E streets NW) on Tuesdays, McPherson Square (15th and K streets NW) on Wednesdays and Dupont Circle on Thursdays, all between 11:30 a.m. and 1:30 p.m.

In Lafayette Square, members of a group clled "98.6" are treatin gunsuspecting sunbathers to "performance art" every Friday at noon through June. Co-directors Carol Vaughn and Debbie Foster said they used to encounter some hostility when they brought their dance company leaping through a park full of picnickers. So this summer, they are creating pieces where bodies are used not so much for movements as for visual art effect.

On Friday's members of 98.6 will eat lunch with everybody else, but in a different way. This week, they plan to pile on top of each other like a piece of sculpture. A few weeks ago, they ate oddly colored food, like pink sandwiches and polka dot potato chips. Last Friday, they ate lying down. Most passerby had the same comment - "weird" - but that was after they stopped to smile.

For those seeking something more traditional, St. John's Church on Lafayette Square offers an organ recital in the sanctuary at 12:10 p.m. each Wednesday. The concerts are offered year-round.

If visitors need sustenance for the body as well as the soul, they can stop by the parish house next door - that is, if they speak French. On Wednesdays between 11:30 a.m. and 1:30 p.m., Dr. Herbert Stein-Schneider, minister for the French Congregation, and his wife serve a fixed-menu lunch for $3.50. The cuisine is French and so is the conversation, for no English is allowed.

There is a lecture or slide show as well.

Moving west to the Kennedy Center, the Performing Arts Symposium will continue each Wednesday at noon throughout the summer, either at the American Film Institute or at another of the Kennedy Center theaters. Although specific guest have not yet been scheduled the usual format includes a lecture or demonstration by dancers, actors, playwrights, conductors or other performing artists, followed by questions from the audience.

The organ demonstrations will continue, too, on Thursdays at 1 p.m. There is a demonstration of the Great Filene Organ in the Concert Hall, which is alternated with a presentation, at the American Film Institute, on the role of the organ in silent films.

Across town on Capitol Hill, folk music will fill the air the last Thursday of every month through October on the main steps of the Library of Congress, right over the Neptune fountain. Next week's concert will feature Arab musicians, stick dancers and belly dancers followedd by bluegrass on June 29 and Cajun music on July 27.

There is music and dance on the other side of the Library of Congress on the first Wednesday of each month, in the sanctuary of St. Mark's Episcopal Church at 3rd and A streets SE. Local musicians and singers and the St. Mark's Dance Company perform from 11:30 a.m. to 1:30 p.m. Voluntary donations are requested for the performers by the congregation goes into a fund to restore the churh's stained glass window.

On June 7, the St. Mark's Dance Company will perform "Luminous Flux," choreographed by Greg Reynolds, a former member of the Paul Taylor Company. On July 5, the St. Mark's Junior Company will present "Gospel Suite," choreographed by instructor Rosema Brooks. No Concert is planned for August.

Soap opera fans who run home and watch TV at lunchtime soon can hop on the subway, instead, and go to the ASTA Theater at 507 8th St. SE. On June 9, ASTA plans to unveil a spoof on Washington affairs, political and otherwise, entitled "In the Pursuit of Happiness."

New episodes are scheduled for Mondays, Wednesdays and Fridays, with two 25-minute shows between noon and 2 p.m. A $3.50 admission charge will include a box lunch prepared by the Townhouse Restaurant.

That's some of the organized entertainment. Lunchtime strollers, downtown or on the Mall, are likely to tun across impromptu performances as well. For instance, Bob Devlin, after three years of playing his guitar, harmonica and cymbal at 18th and M streets NW and other nearby corners, almost has become a lunchtime institution. But many other musicians, moved to perform outdoors by the spirit of spring or a cash squeeze, defy listing. You'll have to find them yourself.