Highlight of the week: The Washington Opera's new "Eugene Onegin," Saturday night in the Kennedy Center Opera House. Those who do not have tickets for the opera opening might try to get tickets for Stravinsky's "L'Histoire du Soldat," Saturday night at the Dumbarton United Methodist Church. This will be a benefit concert by members of the National Symphony for the Dumbarton Concert Series and the H. Stevens Brewster Memorial Scholarship Fund.

Orchestras active today include the Virginia Chamber Orchestra, tonight and tomorrow night at the Wolf Trap Barns, with Nadja Salerno-Sonnenberg as soloist in Vivaldi's "The Four Seasons"; the Washington Conservatory Orchestra this afternoon at Dumbarton Methodist Church; the Mount Vernon Chamber Orchestra, this evening at St. Aidan's Episcopal Church, Alexandria.

Other highlights today: The finals of the Friedheim Awards, this afternoon in the Terrace Theater; the Oratorio Society's performance of Handel's "Solomon" tonight in the Concert Hall. The opening of the Washington Music Ensemble's Festival of French Music, tonight at American University.

The Contemporary Music Forum opens its season with a well-varied program including taped music, improvisation and an old-fashioned string quartet tomorrow night at the Corcoran. Tomorrow night at the Kennedy Center, the Detroit Symphony makes its second Washington appearance of the month with Gunther Herbig conducting and Julia Migenes-Johnson as soloist.

The Library of Congress Founder's Day Concert will feature soprano Phyllis Bryn-Julson, pianist Donald Sutherland and the Atlantic String Quartet, Wednesday night in the Coolidge Auditorium.

The University of Maryland will open its Handel Festival, Thursday night in the Campus chapel, with the pastoral opera "Acis and Galatea." Also on Thursday: The National Symphony Orchestra, with Rafael Fru hbeck de Burgos conducting, will perform Mahler's Second Symphony; a midnight organ concert in the Kennedy Center Concert Hall will feature music appropriate for Halloween.

The Salomon String Quartet, made up of members of the Academy of Ancient Music, will be featured Friday night at the Library of Congress. The 20th Century Consort will feature music by Pulitzer Prize winners Stephen Albert, George Crumb and Joseph Schwantner, Saturday in the Hirshhorn Musuem.

Also opening their seasons on Saturday night: Paul Hill's Washington Singers at the Kennedy Center and the Washington Chamber Society at Wesley United Methodist Church. Hesperus, with a program of American baroque music, will perform at Georgetown University's Gaston Hall.

Also noteworthy on Saturday night: Itzhak Perlman's recital in the Kennedy Center Concert Hall; a performance of the "Water Music" in the University of Maryland Handel Festival. DANCE

The Royal Winnipeg Ballet appears in the Washington area tonight for the first time since its Kennedy Center performance 10 years ago. One of Canada's three major ballet troupes, the company will present a program including works by Balanchine, Araiz, Kylian and Nils Christe, at Montgomery College's handsome Performing Arts Center in Rockville. The Margaret Jenkins Dance Company offers a lecture-demonstration (with audience discussion) Monday night, followed Tuesday evening by a full performance, both at Dance Place. San Francisco's Jenkins, a member of Twyla Tharp's original company, among others, is one of the nation's most influential choreographers and teachers. FILM

Tuesday at 8 in the Carmichael Auditorium of the American History Building at the Smithsonian, the Washington premiere of "Robert Frost," a documentary on the life of the celebrated poet. With an introduction by Washington poet David McAleavey.

Thursday at 7 at the National Archives, David Lean's "Bridge Over the River Kwai." Free. Call 523-3000 for details.

The Soviet Cinema series continues at the Biograph this week with Grigory Kosintsev's "Hamlet" and Andrei Konchalovsky's "Uncle Vanya," Tuesday through Thursday.

Opening Friday at the Outer Circle, Emir Kusturica's "When Father Was Away on Business." Among current releases, Martin Scorsese's flawed but often brilliant "After Hours." POP MUSIC

A Scottish band worth keeping an ear on if only for Mike Scott's synthesis of William Blake and Van Morrison, The Waterboys perform at the Bayou tonight.

Christy Moore, the great Irish folk singer and one of the grandest voices in the idiom, is at Gaston Hall on Friday, with piper Liam O'Flynn supporting.

A tale of two saxophonists: Hard-blowing Johnny Griffin is at Blues Alley tomorrow and the underrated Billy Harper is there on Wednesday.

Two of the most prominent families in Celtic music -- John and Phil Cunningham and Michael and Triona O'Domhnaill -- tour together for the first time as Relativity. At Saba on Tuesday.

Home-town boy makes real good: Nils Lofgren, just coming off a 15-month world tour as the guitarist for Bruce Springsteen, unveils his new band at the Warner on Thursday.

Betty "Bebop" Carter remains one of the most uncompromising vocalists working in the jazz idiom. At Blues Alley Friday through Sunday. THEATER

In "'night Mother" (at Arena's Kreeger Theater), a daughter announces to her mother that she has decided to commit suicide. Putting all philosophical questions aside, Pulitzer Prize-winning playwright Marsha Norman chronicles the 90 humble, occasionally funny, minutes that follow. Superlatively acted and meticulously staged, the evening builds to a devastating climax that will send you reeling from the theater.