Meanwhile, “Summer in the City,” a propulsive, apolitical rock song by the New York-based the Lovin’ Spoonful, was climbing the charts to No. 1, reassuring listeners that “despite the heat it’ll be all right.” Sung and co-written by John Sebastian, the band’s frontman, the song was conceived by his younger brother, Mark Sebastian, when he was just 14. Steve Boone, the bass player, contributed the memorable instrumental interlude. The three shared writing credit and continue to reap royalties: The song has endured as an anthem for every heat wave since and has been covered by Quincy Jones, Joe Cocker and Isaac Hayes, among others.

(It will most likely figure prominently at a concert, “Music and Revolution: Greenwich Village in the 1960s,” on Aug. 12 at Central Park’s SummerStage, where Sebastian is part of a lineup that includes José Feliciano and Maria Muldaur.)

[John Schaefer, the host of “New Sounds” on WNYC, shares his 12 favorite songs about New York in the heat.]

In addition to Sebastian and Boone, the original band members (Mark was too young) were Zal Yanovsky on guitar and Joe Butler on drums. Their producer, Erik Jacobsen, helped shape their 1965 debut album, “Do You Believe in Magic,” and their 1966 follow-up album, “Daydream.” Their manager, Bob Cavallo, masterminded the business end. In 1966, the group also supplied the soundtrack to Woody Allen’s “What’s Up, Tiger Lily?” They toured extensively and with their rapid rise to fame, found themselves in need of more material. One day, Sebastian heard something intriguing from his younger brother.