From Sinatra's "Summer Wind" to the astonishing summer of '64 (Martha and the Vandellas' "Dancing in the Street," the Beach Boys' "I Get Around," The Drifters' "Under the Boardwalk") and on to Bananarama's "Cruel Summer" in 1984, Will Smith's "Summertime" in 1991 and Nelly's 2002 sizzler, "Hot in Herre," radio has seared summer songs into the American subconsciousness.

The summer song is often, but need not be, about the summer. It is almost always lighter and brighter than your average pop hit; in the days of transistor radios, the summer song was perfectly suited to the treble-happy Top 40 AM sound, on which bass lines barely made themselves heard, let alone felt.

Even today, summer songs remain frothy and frilly, designed expressly to seep into that soft spot in your memory where you store July's longing, August's climax and September's parting.

"You always want a summer song," says Jeff Wyatt, regional vice president of programming for Clear Channel and program director at Hot 99.5. "You'd love to have one that has meaning to you. 'Hello It's Me' by Todd Rundgren meant one girl to me. I can still see myself sitting on the curb right in front of her house, which was so stupid, but I was a teenager and that's what I did.

"Summer songs match up so well with where people's minds are at in the summer, at times when the feeling is that possibilities are endless, the weather is good and adventures are aplenty."

Rundgren's song actually became a hit in the cold of winter, but it's the content and style of a song that determines how it fixes in listeners' minds. Some classic summer songs, such as Sinatra's "Summer Wind," which first hit the charts in the autumn of 1966, only gain their summer-song stature the second time around -- either the summer after they make the charts, or later, as an oldie.

Summer songs are usually love songs, but they're also about setting forth into the world and being stupid and crazy. The Go-Gos took us on "Vacation" and Sergio Mendes and Brasil '66 lifted us into a reverie about "The Look of Love," while the Starland Vocal Band crooned about the pleasures of "Afternoon Delight."

"It's the vibe and the tempo, it's a family reunion, cookout, picnic kind of sound," says Darryl Huckaby, program director at WKYS (93.9 FM). "The classic R&B summer song is Will Smith's 'Summertime,' and Nelly and Kelly Rowland had that same feeling with 'Dilemma' a couple of years ago."

In Washington, you know the heat has arrived to stay when WKYS and some of the other urban stations haul out the summer hit by the Blackbyrds, "Rock Creek Park," a piece of '70s jazz-funk that, to borrow another station's erstwhile slogan, sounds like Washington. "It's about being in the park and hanging out and feeling light and smooth," Huckaby says.

Summer songs are less a presence today than they were in the '60s and '70s, when the whole nation shared one source of pop tunes, Top 40 radio. "There weren't nearly so many choices then," Wyatt says. A summer song would be on the radio so frequently that people hanging out at the beach or the pool would hear it literally hundreds of times, making the songs almost certain to link up with peak summer experiences.

Summer hits seemed to win popularity more organically in that era, and the mechanics of creating a hit song were much simpler: "Labels just sent record guys into stations and talked up the records," Wyatt says. Even in the heyday of payola, when deejays were being paid to spin certain tunes, summer songs snaked their way up the charts primarily through repetition on the air and word of mouth on the street and at the beach.

Today, by contrast, a far more complex and splintered marketing approach includes efforts to spread word about a song on the Internet, on radio and cable television, and via street crews hired by record labels to work the beaches and the nightclubs, "to get that record virally happening," as Wyatt puts it.

A few summer songs manage to thread their way into the common culture even in a listener's world of 50 radio stations, 100 satellite channels and infinite choices for the iPod. Fat Joe's version of Nelly's "Get It Poppin' " is a light, bubbly number that Wyatt sees moving up this summer, and the most requested song at Hot 99.5 is a just-released remake of "Listen to Your Heart" by D.H.T. that shifts between plaintive ballad passages and a harder club sound. Huckaby predicts big things for Bow Wow's "Let Me Hold You," a relatively smooth and summery hip-hop number about longing that harks back to the classic '60s Motown sound.

But few songs today dare to traffic in the innocence and silliness of the summer songs that dominated the charts from the '60s through the '80s. Those sounds of summer stick with generations of listeners like the perfect summer crush: B-52's "Love Shack" (a fall hit originally but eventually a summer standby), Sly and the Family Stone's "Hot Fun in the Summertime," and "Sealed With a Kiss," which made the hit charts in at least three versions, by Brian Hyland (1962), Gary Lewis & the Playboys (1968) and Bobby Vinton (1972), each of whom broke a million hearts simply by singing, "I don't wanna say goodbye for the summer."