The classical music season, which begins formally Thursday with the National Symphony Orchestra's commemoration of Nadia Boulanger, will be the busiest in Washington's history.

Busiest but not necessarily most eventful.

The number of concerts in and around Washington will reach an all-time high, but the season, as far as it can be predicted now, will not have any events of international magnitude (such as Mstislav Rostropovich's 60th birthday or the premiere of Gian Carlo Menotti's "Goya" last season) to focus the world's attention on Washington.

Music in Washington will enter the international spotlight later this month, when pianist Vladimir Feltsman makes his American debut in an invitation-only concert at the White House. But the attention Feltsman is getting now is not purely musical; it is a matter of human interest, inspired by the years of punishment he suffered after applying for an exit visa from the Soviet Union in 1979.

Chamber music will be the most abundant classical music in Washington, as it has been in the past. Washington may lead the world in the quality and quantity of its chamber music and almost certainly leads the world in the number and quality of its free concerts. When the Juilliard Quartet opens the season at the Library of Congress next month, it will be the kind of event that would make headlines anywhere else: a series of concerts by one of the world's leading ensembles at a price of 25 cents per ticket.

In Washington, it is part of an old tradition and taken for granted, as are the frequent appearances of the Tokyo, Cleveland, Guarneri and Emerson quartets, whose tickets cost somewhat more. Unlike those listed above, the Kronos Quartet (a specialist in ultramodern music with a strong following among young people) does not have a residence in Washington. But it will be here three times during the season, under the auspices of several different presenters. Quartets permanently resident in Washington include the Manchester, made up of National Symphony players, and the Smithson, which plays on old instruments at the Smithsonian.

The Corcoran Gallery, with the Tokyo and Cleveland quartets, contributes significantly to the quality of musical life in this city, as do other museums and libraries: the National Gallery, the Folger Shakespeare Library and several of the Smithsonian's museums: the Hirshhorn, the Renwick, the Museum of Natural History and the Museum of American History.

The Phillips Collection continues to sponsor concerts every Sunday afternoon, but it now asks its visitors for contributions. This phases out a significant venue for free concerts in Washington, but the National Gallery continues to give free concerts in the East Garden Court on Sunday evenings; there are frequent (and increasing) free lunch-hour concerts at the World Bank and in downtown churches; and the Friday Morning Music Club gives regular free concerts -- on Friday mornings, of course. This year, some of the club's concerts will be given at Strathmore Hall in Montgomery County, a performing arts center that has become a significant part of the area's musical life in recent years.

The rise of Strathmore Hall, miles outside of Washington on Rockville Pike, is part of a phenomenon that is not exactly spectacular but highly significant: the growing suburbanization of music in the Washington area. A number of longstanding suburban series, including those at the Wolf Trap Barns, the National Institutes of Health, the Jewish Community Center in Rockville and University Community Concerts at the University of Maryland, have been joined in recent seasons by first-class concert series at George Mason University in Fairfax, by the Candlelight Concerts in Columbia, the Alexandria Recital Series, the Great Falls Concert Series and an active program at Montgomery College, among others.

At least two suburban orchestras, the Montgomery Chamber Orchestra and the Fairfax Symphony, perform regularly at a high professional level, and many others -- including the Prince George's Philharmonic, the Arlington Symphony, the Alexandria Symphony and the McLean Symphony -- are constantly improving. The Virginia Chamber Orchestra's music director, Andrew Litton, has become one of the most eagerly sought guest conductors on the international scene in the last few years.

But orchestral activity remains intensive downtown, with the National Symphony standing out among many other local orchestras: the National Gallery Orchestra, the Handel Festival Orchestra, the American Chamber Orchestra, the Smithsonian Chamber Orchestra, the Air Force Sinfonietta, the Levine Chamber Orchestra, the Friday Morning Music Club Orchestra, the Georgetown Symphony Orchestra, the Catholic University Orchestra, the D.C. Youth Orchestra and the Amadeus Orchestra, to name a few.

If this is not enough for the orchestra-hungry, the Washington Performing Arts Society is planning to bring a wide variety of visiting orchestras to town between now and the New Year, including (in chronological, not qualitative order) the Mantovani Orchestra, the Philadelphia Orchestra, the Royal Philharmonic, the Tonku nstler Orchestra of Vienna, the Moscow Virtuosi, the Central Philharmonic of China, the Academy of Ancient Music, the Detroit Symphony, the Leningrad State Symphony, the London Philharmonic, the Dresden Staatskapelle and the Mozarteum Orchestra of Salzburg.

Orchestra-importing (at least for chamber orchestras) is even becoming a possibility for organizations with much smaller budgets than the WPAS. The Dumbarton Oaks Friends of Music Series, a private series open only to subscribers, will get on the orchestral bandwagon, opening its season with two performances by the Sofia Chamber Orchestra later this month. University Community Concerts will bring the Orchestra of the Eighteenth Century to the University of Maryland in November, and the Orquesta da Camara Brasilena in November at the Organization of American States. This might be remembered as the Season of the Visiting Orchestras, except that it is likely we will see even more in a future year.

The Washington Opera will present a mixed bag of a season with something to interest nearly anyone who has a taste for opera, though it will include no Mozart, no Verdi, no Russian opera and (as usual) no Wagner.

Two of the season's three Italian operas will be recycled from earlier seasons: Rossini's "L'Italiana in Algeri" and Puccini's "Madama Butterfly." A third Italian opera, Mascagni's "L'Amico Fritz," will be a new production and will inaugurate the company's performances in the Eisenhower Theater. There will be two French operas, a genre not much favored by the Washington Opera in recent seasons: a new production of Gounod's "Romeo and Juliet" and a revival of Massenet's "Cendrillon," starring Frederica Von Stade, who also sang the title role the last time it was done here.

Perhaps the most promising new productions will be those sung in German (Beethoven's "Fidelio") and English (Menotti's "The Consul" and Gilbert and Sullivan's "Ruddigore.") Gian Carlo Menotti will be the stage director for "The Consul." Considering the impact of other operas he has stage-directed in Washington, "The Consul" is the odds-on favorite to be the highlight of the season.

Without attempting to compete with the Washington Opera, a number of smaller companies will contribute to the diversity of opera in the area -- the Prince George's Civic Opera, for example, which will be offering "The Merry Widow," and the National Lyric Opera, which will be performing at the French Embassy.

Music Director Mstislav Rostropovich will conduct the National Symphony's opening concert, dedicated entirely to modern American music. Two of the composers, Elliott Carter and Walter Piston, were students of Nadia Boulanger, whose centennial is being observed this month. The third, William Schuman, represents a small but significant minority among notable American composers: those who did not study with Boulanger. His "On Freedom's Ground" will be performed at the opening concert to celebrate the anniversary of the Constitution.

In the NSO's second week, Rostropovich will include the "Symphonie fantastique" of Berlioz on his program for the first time in Washington. Guest conductors scheduled to perform with the NSO between now and the New Year include Lorin Maazel, Gerd Albrecht, Catherine Comet, Tama's Vasary, Krzysztof Penderecki and Raymond Leppard. The NSO's Exxon/Arts Endowment conductor, Fabio Mechetti, will make his subscription series debut on Oct. 22, and principal guest conductor Rafael Fru hbeck de Burgos will conduct during two weeks in October and November. Guest artists for NSO pops programs will include the King's Singers, comedian Sid Caesar and the National Tap Dance Company of Canada.

Three noteworthy music festivals are scheduled for the fall season in Washington. The Schubert, Schubert and Schubert Festival, Oct. 23-25, will include among its artists the New World String Quartet, an American ensemble in residence at Harvard University, as well as Austrian mezzo-soprano Julia Bernheimer and Austrian pianist Robert Lehrbaumer.

The University of Maryland Handel Festival will open Oct. 29 with a repeat performance of Handel's opera "Tolomeo," which created a sensation when it was performed on the College Park campus last season. Once again, Nicholas McGegan will conduct. The festival will reach its climax and conclusion on Nov. 1 with the University of Maryland Chorus performing "Israel in Egypt" -- a choral spectacular for a spectacular chorus.

The Washington Music Ensemble's second Festival of American Music, beginning Nov. 7 with a "Sousa Birthday Celebration," will continue through Nov. 22 at several locations, including American University, the National Press Club and the Kennedy Center. The festival will include several world premieres as well as familiar works by such composers as Copland, Ives and Siegmeister. A piano recital by Alan Mandel on Nov. 13 will feature unpublished piano music by Ives and the world premiere of his "The Celestial Railroad."

When it is not bringing in orchestras from the far corners of the world, the Washington Performing Arts Society will sponsor such singers as Leontyne Price, Luciano Pavarotti, Ben Holt and Arleen Auge'r, violinist Mark Peskanov, pianists Rudolf Serkin, Andre' Watts and Andrea Luccesini, the trio of Isaac Stern, Yo Yo Ma and Emanuel Ax, and the concerts of the Handel Festival Orchestra, which will escalate from single performances of each program to two performances. The orchestra will also be featured, with singers, in a semistaged concert performance of Handel's opera "Rinaldo."

Other major importers of musical talent include the Kennedy Center, particularly for its series of Terrace Concerts, the Library of Congress and the University Community Concerts at the University of Maryland. Attractions in the Terrace Concerts this season will include Music from Marlboro, a Gershwin program, the Guarneri and Colorado string quartets, soprano Benita Valente, pianists Grant Johannesen, Peter Serkin, Rian De Waal, Sequeira Costa, Santiago Rodriguez and Andrzej Wasowski, and the Cleveland Octet. The Terrace will also be the scene for the Theater Chamber Players' adventurous programming and high-level musicianship. There are no plans for opera in the Terrace this season -- an incalculable loss to lovers of that art.

In the Kennedy Center Concert Hall, the Chamber Music Society of Lincoln Center will continue its series of 7 p.m. Wednesday evening concerts as in previous years.

Highlights of the Library of Congress season will include a recital by soprano Phyllis Bryn-Julson and pianist James Tocco, a program by clarinetist David Shifrin and pianist Menahem Pressler, the Pro Arte Quartet, London Baroque and the Da Capo Chamber Players.

University Community Concerts, opening with a recital by pianist Alexander Toradze, will also include a complete Beethoven cycle by the Cleveland Quartet. The most distinctive series offered by University Community Concerts, and one whose success has surprised the sponsors, is the Olde Musicke Series, which neatly supplements the performances of old music on old instruments given by such resident groups as the Folger Consort, the Smithsonian Chamber Players, Hesperus and Wondrous Machine. This season, the Olde Musicke Series will bring in an outstanding array of specialized groups, including the Sequentia Ensemble, Les Arts Florissants, Pomerium Musices and Calliope.

In contemporary music, the highlight of the season will be the finals of the Kennedy Center/Friedheim Awards for new American music -- this year for chamber music. A new activity in a similar vein is the David Lloyd Kreeger Composition Competition, which will climax with a concert Nov. 1 at Catholic University's Benjamin T. Rome School of Music. Continuing attention to new music may be expected from the 20th Century Consort, the Contemporary Music Forum, the University of Maryland's 20th Century Ensemble, the Washington Music Ensemble, Music of the Spheres and Amaranth. Living composers featured in the Kennedy Center's American Composers Series will include Otto Luening and Mario Davidovsky.

In its new "Washington Sings" series, the Paul Hill Chorale will feature music of Washington composers in five concerts given at various locations. It will also present contemporary music in an "Andrew Lloyd Webber Family Concert" Oct. 24 and its "American Excursion" (with two world premieres) on Nov. 15.

There will be at least two performances of Beethoven's magnificent "Missa Solemnis" in Washington this season. The Paul Hill Chorale will give one in March, and the Cathedral Choral Society in November. Mozart's Requiem and Vivaldi's Gloria will highlight the Oratorio Society's fall season, while the Choral Arts Society will perform Rachmaninoff's "The Bells" and Mozart's great Mass in C Minor. Among the countless Christmas programs planned for December, special imagination is shown by the Arlington Choral Society, which will do Respighi's "Laud to the Nativity," and the Montgomery Chamber Orchestra, which will offer Berlioz's "L'Enfance du Christ." Some highlights of the fall season are noted briefly below.

SEPTEMBER: Today marks the season opening for the Alexandria Recital Series, the Virginia Chamber Orchestra and the Phillips Collection. The Beethoven Society will open its season tomorrow night at the German Embassy with an all-Beethoven program, and the National Symphony and the Handel Festival Orchestra both open their seasons on Thursday night.

Next week's highlights will include a performance by the Kronos Quartet on the 19th, a tribute to Nadia Boulanger by performers from the Shenandoah Conservatory on the 20th, a recital by baritone Ben Holt on the 21st and a program of operatic highlights by the National Lyric Opera Company on the 22nd and 23rd, opening the season at La Maison Francaise, the fine little auditorium in the French Embassy. On the 25th, there will be a program of music by Sigmund Romberg in the Baird Auditorium, the Manchester String Quartet will open its season at the Holton-Arms School and the Mantovani Orchestra will play at the Kennedy Center. The Philadelphia Orchestra will make the first of its three Washington appearances on the 30th.

OCTOBER: An unusual program of contemporary music will be given by bass-baritone Lieuwe Visser and pianist Robert Nasveld at the Library of Congress on the 3rd. Violinist Adela Penåa, winner of the 1985 Friday Morning Music Club competition, will perform at the Phillips Collection on the 4th, and the National Gallery Orchestra, conducted by George Manos, will open its season the same day in the East Garden Court.

On the 7th, the Washington Performing Arts Society will present the Royal Philharmonic, Andre' Previn conducting, at the Kennedy Center -- the first of many distinguished visiting orchestras it will bring to Washington this season. Mezzo-soprano Ute Jahr will open the concert season at Mount Vernon College on the 13th. The Cleveland Quartet will open its season at the Corcoran Gallery on the 16th.

The Folger Consort, the Theater Chamber Players, the Fairfax Symphony Orchestra, the Montgomery Chamber Orchestra the Alexandria Symphony Orchestra and the American Chamber Orchestra will all start their seasons on the 17th. The same evening, the Cleveland Quartet will begin its Beethoven cycle at the University of Maryland in the Community Concert Series.

Luciano Pavarotti will sing at Constitution Hall on the 18th. The Smithsonian Chamber Players will open their season on the 23rd with cellist Anner Bylsma as guest artist. On the 23rd and 24th, the Washington Chamber Society will open its season at two performing spaces new for this ensemble: Montgomery College and La Maison Franc aise.

Notable concerts on the 24th will include Lontano, a contemporary music ensemble from England, at the Hirshhorn; the Korean Concert Society (young musicians from Seoul) in the Terrace Theater; bassoonist Linda Harwell at the Corcoran Gallery; the Masterworks Chorus and Orchestra at Bradley Hills Presbyterian Church.

The Kennedy Center/Friedheim Awards concert will be given on the 25th in the Terrace Theater. The Tokyo String Quartet will open its season at the Corcoran Gallery on the 30th and the Emerson String Quartet will open its season in the Baird Auditorium on the 31st. The Prince George's Philharmonic will open its season on the same day.

NOVEMBER: November will be a month for singing. Its highlight will be the opening of the Washington Opera's season on the 7th with Gounod's "Rome'o et Juliette." It will be followed by "Madame Butterfly" a week later. Other noteworthy concerts will include the Oratorio Society's performance of Mozart's Requiem and Vivaldi's Gloria on the 8th, the Cathedral Choral Society's Missa Solemnis on the 15th, Choral Arts Society's performance of Rachmaninoff's "The Bells" and Mozart's Mass in C minor on the 22nd. The Smithson String Quartet will open its season on the 10th.

DECEMBER: The Washington Opera will move into the Eisenhower Theater on the 19th with Mascagni's "L'Amico Fritz," the first of four productions to be presented in that theater. The others will be "Ruddigore" (opening on the 21st), "L'Italiana in Algeri" (Jan. 2) and "The Consul" (Jan. 23). Then opera will return to the Opera House with "Fidelio" (Feb. 20) and "Cendrillon" (Feb. 27).

The Serkins, pe`re et fils, will perform here in December: Peter in the Terrace Theater on the 10th; Rudolf in the Concert Hall on the 13th. The 20th Century Consort will open its season on the 5th at the Hirshhorn. The National Symphony's "Messiah" will have four performances on the 17th through the 20th. The Kennedy Center's "Messiah" sing-along will be held on the 23rd, and the year will conclude with the traditional "Night in Old Vienna" at the Kennedy Center.