The National Symphony Orchestra is going Hollywood this summer.

Having just recorded Stephen Albert's Pulitzer Prize-winning symphony, "RiverRun," on the Delos label, the NSO, under the direction of Mstislav Rostropovich, will record the sound track for a motion picture version of Mussorgsky's "Boris Godunov." The recording session will be in the Kennedy Center's Concert Hall next month and the movie's due out in 1988. On the eve of the recording (7 p.m. July 6), the NSO also will perform a one-time-only concert of "Godunov." Tickets range from $5 to $35. Call 785-8100 for information.

The NSO grabs more kudos this week by being the guest orchestra at the 1987 Casals Festival in Puerto Rico. Only one orchestra each year is invited to participate in the festival. For die-hard and sun-hungry fans, the NSO will play on Tuesday, Wednesday, Friday and Saturday at the Sala de Festivales in San Juan.

The Rising Arts Budget D.C. a cultural desert? It's not for lack of money.

An update of state arts agency legislative appropriations, released by the National Assembly of State Arts Agencies, shows that the District ranks third in per capita spending in the United States. This year's budget showed a 34.1 percent rise in spending on the arts -- in 1986 the District spent $1.76 million; in 1987, $2.37 million.

Three small District visual arts venues have gotten $75,000 of the $1.86 million the National Endowment for the Arts is giving in that category this year. The spunky Fondo Del Sol museum, located in a Dupont Circle town house, received $15,000 for exhibits by visual artists from diverse cultural and ethnic backgrounds; the National Association of Artists' Organizations got $10,000 for semiannual board meetings and bimonthly publication of an arts newsletter; and the Washington Project for the Arts got a $50,000 for exhibitions, programs and an artists' bookstore. Grant proposals for next year are due today.

The Best and Brightest Two local young artists have been named U.S. Presidential Scholars in the Arts. Marc Abramson, a senior at Sidwell Friends, won for writing, and Leslie Holt, a senior at Bethesda's Walt Whitman High School, won for visual arts. The pair, along with 17 others from across the country, were chosen for their outstanding performance in the 1987 Arts Recognition and Talent Search of the National Foundation for Advancement in the Arts. For their talents, there'll be art and writing exhibits, which started yesterday, a dance and music gala at the Kennedy Center tonight and a chance to meet President Reagan at the White House on Wednesday. They'll also meet Supreme Court Justice Sandra Day O'Connor and former U.N. ambassador Jeane Kirkpatrick.

The sixth annual National Heritage Fellowships will go to 13 of the United States' traditional artists, representing an unusual array of talents, including a carnival mask maker from Puerto Rico and a kabuki dancer from Los Angeles. Given by the National Endowment for the Arts, the $5,000 awards will presented here in October. Winners are: Juan Alindato (carnival mask maker, Puerto Rico); Louis Bashell (accordionist and polka master, Wisconsin); Genoveva Castellanoz (flower crown maker, Oregon); Thomas Edison (Brownie) Ford (cowboy singer and storyteller, Louisiana); Kansuma Fujima (kabuki dancer, California); C.J. Johnson (Afro-American religious singer and orator, Georgia); Raymond Kane (slack key guitarist, Hawaii); Sylvester McIntosh (Crucian singer, band leader and instrumentalist, Virgin Islands); Wade Mainer (Appalachian five-string banjo picker and singer, Michigan); Allison (Tuddy) Montana (Mardi Gras big chief and costume maker, Louisiana); Alex Moore (blues pianist, Texas); Emilio and Senaida Romero (crafts workers in tin and embroidery, New Mexico); and Newton Washburn (split ash basket maker, New Hampshire).

Summer Sounds For this week's outdoor concerts, the good news is that the cicadas are mostly gone. The bad news: Here comes the humidity. So what? These more offbeat summer sounds will cool you off:

On Thursday, the American Folklife Center presents Afghan and Iranian traditional music for free on Neptune Plaza in front of the Library of Congress. An Afghan musician will play the rehab, dotar, tabla and harmonium, and his Iranian counterpart will strum a tar. To find out what these exotic things are, go from noon to 1:30 p.m.

If the heat gets too much, head inside the cool and still National Shrine of the Immaculate Conception to hear the music of the 25-year-old organs. Concerts will be given there each Sunday evening at 6, through Aug. 30. Up this week: Vivaldi, Handel, Liszt, Prokofiev and Stravinsky.

'Helga' Open Evenings And finally, officials at the National Gallery of Art report that although there are long lines in the morning for the current "Helga" exhibit by Andrew Wyeth, the place is like a ghost town in the evenings. The NGA is open late in the summer. Call 737-4215 for details.