TRADITIONALLY, the peak periods of movie attendance are the summer and the Christmas season, when school holidays increase the likelihood that young people and families will look to films for entertainment.

Consequently, one might expect something light-hearted, festive or inspirational about Christmas openings. But the record of the past decade indicates that audiences have no clear seasonal preferences. The last picture with a definite thematic link to Christmas was probably "Scrooge" -- a flop -- and it's been some time since the major studios conceived material like "Holiday Inn" or "Miracle on 34th Street."

In fact, the Christmas "traditions" of recent years are both varied and secular. Clint Eastwood, of all personalities, has become a Christmas staple. The trend began with "Dirty Harry" in 1971 and continued with "Magnum Force" in 1973, "The Enforcer" in 1976 and "The Gauntlet" in 1977. The Eastwood for this Christmas is "Every Which Way But Loose," a knockabout farce inwhich Eastwood plays a brawling trucker and evidently submits to consistent upstaging by an orangutan named Clyde. And audiences expect a major new release or important revival from the Disney organization, which this year is reissuing the greatest of its animated features, "Pinocchio."

Moreover, many successful Christmas releases are not planned that way. One of the great hits of last Christmas, Steven Spielberg's "Close Encounters of the Third Kind," was originally intended for a summer debut. So was "Superman," the likeliest crowd-pleaser among the new pictures opening this Christmas.

The popular films of Christmases past have been as diverse as "The Goodbye Girl," "Rocky," "The Pink Panther Strikes Again," "Silver Streak," "Young Frankenstein," "The Sting," "Sleeper," "Love Story" and "The Owl and the Pussycat," as well as "Saturday Night Fever," "One Flew Over the Cuckoo's Nest," "The Man Who Would Be King," "The Magic Flute," "Godfather II," "The Exorcist," "The Last Picture Show" and "The Wild Child." The only certainty is that each holiday season brings about a dozen new releases.

This year's Christmas list appears a trifle slim: 10 new titles plus two revivals -- both of them, "Pinocchio" and "The Thief of Bagdad," quality items. The parade begins on Friday, Dec. 15, with "Superman" (see accompanying article) and "Oliver's Story," John Korty's film of Erich Segal's follow-up to "Love Story," which finds Ryan O'Neal as the bereaved Oliver Barrett IV finding love anew in the company of Candice Bergen as a wealthy divorcee.

Four pictures open on Wednesday, Dec. 20: As well as the new Eastwood, there is "Brass Target," a melodrama of conspiratorial speculation about the auto accident that fatally injured Gen. George Patton in December of 1945, with George Kennedy as the general and Robert Vaughn, Patrick McGoohan, John Cassavetes, Max von Sydow and Sophia Loren as suspicious parties. Frank Pierson's "King of the Gypsies" dramatizes Peter Mass' non-ficiton account of a dynastic dispute in the gypsy subculture of the United States, with a promising cast that includes Sterling Hyden, Judd Hirsch, Susan Sarandon, Brooke Shields, Annette O'Toole, Michael V. Gazzo, Annie Potts, Shelley Winters and newcomer Eric Roberts. And "The Thief of Bagdad," the 1940 Alexander Korda production that represented the height of special effects fantasy at its time, still retains considerable verve and charm, thanks to the luster of vintage Technicolor and the appeal of Sabu at his most engaging.

A second quartet appears Friday, Dec. 22. "California Sutie," Neil Simon's reworking of his hit stage comedy about the crises faced by several guests at the Beverly Hills Hotel, has Herbert Ross directing the intriguing tandems of Jane Fonda and Alan Alda, Michael Caine and Maggie Smith, Walter Matthau and Elaine May, and Bill Cosby and Richard Pryor. "Force 10 From Navarone," is a belated sequel to "The Guns of..." with the late Robert Shaw, Harrison Ford, Edward Fox, Carl Weathers and Franco Nero trying to pick up where the earlier commandoes left off. "Invasion of the Body Snatchers," Phil Kaufman's Abudget remake of Don Siegel's B-budget supernatural horror classic, brings together Don Sutherland, Leonard Nimoy, Brooke Adams, Veronica Cartwright and Jeff Goldblum as a group of San Franciscans alerted to the threat of souldestroying pods from an alien universe. And in "Moment by Moment," a melodrama of illicit romance set at Malibu, a restless housewife played by Lily Tomlin finds herself attracted to a young drifter played by John Travolta.

Finally, a pair of delightful Christmas Day arrivals: "Pinocchio," in its first revival in a decade, and "Movie Movie," a witty pair of miniature features -- "Dynamite Hands" and "Baxter's Beauties of 1933" -- conceived in loving parody of early '30s entertainments by writers Larry Gelbart and Sheldon Keller. Admirably directed by Stanley Donen, it has a dynamite cast of farceurs including such familiar names as George C. Scott, Eli Wallach, Art Carney and Red Buttons and a spledid group fo young performers, most in their first movie roles, who ought to be headed for stardom -- Harry Hamlin, Barry Bostwick, Ann Reinking and Rebecca York.

Happy holidays.