Two blockbusters, both by the phenomenal young filmmaker Steven Spielberg, are sure to dominate 1982's summer movie season.

"E.T.," Spielberg's inspired and enchanting story of an extraterrestrial creature stranded on Earth, is prime candidate to become the overwhelming hit of the season, and probably the year. And his gothic horror thriller "Poltergeist" is packed with enough incidental humor and visceral sensations to hold off a clutter of challengers for the summer's runner-up spot.

Other leading contenders:

* "Rocky III," the amusing new installment in Sylvester Stallone's ongoing self-help fairy tale about The Importance of Coming Back.

* The movie versions of the Broadway musical fixtures "Annie" and "The Best Little Whorehouse in Texas."

* Adventure thrillers exploiting greater or lesser elements of the fantastic like "Tron," "The Road Warrior," "Megaforce," "Firefox" and "The Thing."

* Comedy vehicles built around performers like Steve Martin in "Dead Men Don't Wear Plaid," Woody Allen in "A Midsummer Night's Sex Comedy," Cheech & Chong in "Things Are Tough All Over," Gene Wilder and Gilda Radner in "Hanky Panky," Bette Midler in "Three of a Kind," Henry Winkler in "Night Shift," the Monty Python troupe in the exquisitely titled "The Secret Policeman's Other Ball" and Mark Blankfield of the "Fridays" TV series in "Jekyll and Hyde . . . Together Again," as well as rather surprising recruits like Al Pacino and Kenny Rogers, both playing bachelor fathers to abandoned broods in "Author Author" and "Six Pack," respectively.

* An animated classic from the Disney studio, "Bambi," along with a new animated feature, "The Secret of NIMH," made by a group of disgruntled Disney animators who hope to revive the tradition.

* A handful of promising dramatic projects that include four literary adaptations--"The World According to Garp," "Tex," "The Chosen" and "The Escape Artist"--and one sturdy original, "An Officer and a Gentleman."

* And, failing all else, the reissues of proven big draws like "Star Wars," "Raiders of the Lost Ark," "Superman," "Stripes" and "The Blue Lagoon."

It was Spielberg's first blockbuster, the brilliantly streamlined film version of "Jaws," that established the recent tendency to look to the summer as the preeminent, pace-setting season for the movie business. Since 1975 when "Jaws" appeared, the big hit of the summer has gone on to be the box-office champion of the year on four other occasions: "Star Wars" in 1977, "Grease" in 1978, "The Empire Strikes Back" in 1980 and "Raiders of the Lost Ark" last year. "E.T." has more than enough potential to make it six years out of eight.

The mixture of summer releases reflects patterns created by the hits of the recent past. The largest single bloc, comedies, includes 12 titles, the revival of "Stripes" and an additional quartet which may or may not be held over for the autumn. In the adventure thriller category, there are 10 new titles and three revivals, most with science-fiction aspects. The horror genre accounts for eight features. Half of them--"The Beast Within," "The Swamp Thing," "A Stranger Is Watching" and "Visiting Hours"--were released in May and are already headed for obscurity, just this side of the oblivion promptly achieved by "Great White," a low-budget "Jaws" ripoff, and "Wrong Is Right," an embarrassing attempt at apocalyptic social satire.

In addition, there are four musicals, a pair of animated features, a pair of soft-core idealizations of Young Romance ("Paradise," a blatant imitation of "The Blue Lagoon," plus "Summer Lovers," the new make-out fantasy from Randal Kleiser, the director of "The Blue Lagoon"), perhaps as many as seven dramas and a stray documentary feature or two. The record of past summers readily explains this preponderance: ""Star Wars," "Smokey and the Bandit" and "The Spy Who Loved Me" in 1977; "Grease," "National Lampoon's Animal House," "Jaws 2," "Heaven Can Wait," "Hooper" and "Up in Smoke" in 1978; "Alien," "Meatballs," "10," "The Amityville Horror" and "Moonraker" in 1979; "The Empire Strikes Back," "Airplane!" "Smokey and the Bandit II" and "The Blue Lagoon" in 1980; "Raiders of the Lost Ark," "Superman II," "Stripes" and "Arthur" last summer.

The number of sequels is relatively modest: "Rocky III" and "Friday the 13th III" plus "Grease II," "Star Trek II," "Shock Treatment" (a belated successor to "The Rocky Horror Picture Show") and "The Road Warrior," a follow-up to the sensational Australian thriller "Mad Max," which wasn't a hit in its dubbed, bungled American release. Woody Allen's latest, "A Midsummer Night's Sex Comedy," was evidently inspired by Ingmar Bergman's delightful boudoir farce "Smiles of a Summer Night," and Jerry Belson's "Jekyll and Hyde . . . Together Again," is a self-evident spoof of the Stevenson classic. There's a sequel to "Airplane!" in the works, but this season's example of that variety of satire is "Young Doctors in Love," Garry Marshall's spoof of soap operas in the "General Hospital" vein. The only out-and-out remake, John Carpenter's "The Thing," sounds more like a deliberate effort to surpass "Alien" at visceral shock effects.

In addition, a strong incentive exists for the performers and filmmakers who contributed to recent hot box-office summers to sustain their participation. Ridley Scott, who directed "Alien," takes a different approach to science-fiction stylization in "Blade Runner," which stars Harrison Ford as a kind of disillusioned bounty hunter, seeking fugitive humanoid "replicants," in a disintegrating high-tech metropolis of the future. Hal Needham, the "Smokey" director, loses Burt Reynolds but commands the Rapid Deployment Force of his fondest patriotic dreams in "Megaforce," an action melodrama about elite warriors costarring Barry Bostwick, Persis Khambatta and Michael Beck.

Meanwhile, Reynolds is represented by his $3 million assignment as the sheriff in "Best Little Whorehouse," opposite Dolly Parton. Hollywood's Other Reliable, Clint Eastwood, also risks a change-of-pace, playing an American jet pilot who comes out of retirement to accept an outrageous spot of espionage, posing as a Soviet flier to hijack a new super-Mig. Even Cheech & Chong are supposed to be taking a new tack with "Things Are Tough All Over," their fourth summer offering, by deemphasizing the drug-centered humor and branching out into sustained impersonations of additional characters.

Regrettably, it won't be possible to measure Brooke Shields' creative growth this summer, but her leading man from "The Blue Lagoon," Christopher Atkins, turns up with Kristy McNichol in "The Pirate Movie," a modernized, rock variant on "The Pirates of Penzance." Atkins' appeal as a teen heartthrob, probably crucial to "Lagoon," may still lag far behind the appeal of Matt Dillon, who has his most likable role yet as the title character in "Tex," a winning movie version of the S.E. Hinton juvenile novel that should restore confidence to the Disney studio, assuming "Tron," a more ambitious and expensive project, doesn't turn things around for them a bit earlier.

It's ironic that "Tron" and "The Secret of NIMH" should be scheduled to open the same day, Friday, July 16. The former is a $17 million gamble by the Disney studio on the imagination of young director, Steven Lisberger, who aspires to create a pictorially unique adventure fantasy by extensive use of sophisticated, abstract computer graphics. His intention is to take us inside a computer system, an ominous electronic environment where imprisoned "users," played by Jeff Bridges, Bruce Boxleitner and others, struggle to survive and overthrow a despotic master programmer, David Warner. Among other perils: The users become combatants in aggressive video games played for keeps.

Having misfired with "The Black Hole," the Disney studio hopes to recoup in a big way with "Tron." In the case of "NIMH," a group of young animators under the supervision of Don Bluth will be attempting to establish a foothold in Disney-type feature animation after leaving the Disney animation family in frustration three years ago. The source material for their daring competitive plunge is an award-winning children's novel, Robert O'Brien's "Mrs. Frisby and the Rats of NIMH," a heroic saga about a widowed mouse who seeks the aid of some mentally superior rats to protect her endangered brood.

For parents, the most gratifying aspect of the summer releases is the abundance of stimulating fare for kids and families. "E.T." alone will make this a summer to cherish, but young moviegoers should also find plenty to like in "Annie," "Tron," "Star Trek II," "Bambi," "NIMH," "Tex," "The Chosen," "The Escape Artist" and an assortment of the available comedies and thrillers.

Universal finds itself in a supremely cozy competitive position this summer, with both "E.T." and "On Golden Pond," a late-1981 release that went into massive distribution in February. Whatever profits accumulate from the remainder of the studio's summer roster--"Conan the Barbarian," "Dead Men Don't Wear Plaid," "The Thing," "The Best Little Whorehouse in Texas," "Fast Times at Ridgemont High"--will put the frosting on an already imposing commercial cake. Even the Cannes film festival added some prestige decoration by honoring a Universal release, "Missing," with the grand prize and then blissing out on "E.T.," a special closing night presentation.