This is about the perfect time of year for this one. The Happenings were a group that mainly took songs that had been recorded by others and put their own spin and harmony on them. "See You in September" was recorded by The Tempos back in 1959. Bob Miranda, who seems to have been the most prominent member of The Happenings described it as "a great song and kind of a bad record." So they did their version in 1966 and it quickly went to Number One on the charts. KHJ played it an awful lot, especially in the Summer…
And in case you're interested, here's the version recorded by The Tempos. Yeah, good song…kind of a bad record…
And if you're really interested, there are other versions of the song online by artists including Julie Budd, Terry Robins and the Playboys, The Symbols, The Chiffons, Gerry and the Pacemakers, Shelley Fabares, Mike Clifford, The Lettermen, The Mike Curb Congregation, The Quotations, Dino Villanueva, Debby Boone, Santo & Johnny and Billy K. and the Seamen.
The Happenings' version is the best in my opinion, followed closely by the recording by The Lettermen which sounds almost identical. The most energetic is probably the one by The Quotations. Do not try to listen to all of them or you'll be begging me to post more versions of the Flintstones theme.