The Sixties were a pretty sunny decade when it came to pop music, as these relatively obscure tunes demonstrate:
The Millennium: Some Sunny Day
Skeeter Davis: Summer Sunshine
Hearts And Flowers: Try For The Sun
See also: Margo
Further research: The Millennium: here and here, Skeeter Davis: here, Hearts And Flowers: here and here.
40 Year Itch : Dabbling Dangerously with Easy Listening
21 minutes ago