Originally recorded by The Tempos (US #23 1959).
Also recorded by The Quotations (1962), The Chiffons (1963), Teddy Robin & the Playboys (1967).
Other hit versions by The Symbols (UK #19 1966), The Happenings (US #3 1966), The Mike Curb Congregation (MOR #15 1972).
From the wiki: “‘See You in September’ was first recorded by the Pittsburgh vocal trio The Tempos (whose members included a pre-‘Rose Are Red’ Bobby Vinton). This first version peaked at #23 in the summer of 1959. The most popular version of ‘See You in September’ was the version by The Happenings in 1966, when it reached #3.