Sly and The Family Stone - Hot Fun in the Summertime medley
This group was very much of its time and yet is timeless with pure genius. Technically, this song was released in 1969, but let us think of it as a 70s hit as well, since it was played throughout the next decade and beyond and shows no sign of stopping at this point.
Nick Gilder - Hot Child in the City
Gosh, remember Nick Gilder? I had forgotten too. But I'll always remember this song, which was on the radio constantly when it was released in 1978.
Walter Egan - Hot Summer Nights
I concede, Walter Egan was responsible for some of the catchiest tunes of the 70s. Some might call them "ear worms," but I don't mind when one of his tunes gets lodged in my head and I can't escape from it for a few days. Must be that soothing countenance he wears so casually, like a shiny, satin, big-collared shirt.
Mungo Jerry - In The Summertime
I have nothing to add other than: Mungo Jerry for the win!