The "rain coming down on a sunny day" is a literal description of a sunshower, used here as a metaphor for the band's predicament: they were at the sunny zenith of their fame, yet felt miserable and depressed.
Released in early 1971, "Have You Ever Seen the Rain?" by Creedence Clearwater Revival (CCR) remains one of rock's most enduring paradoxes. While its upbeat, roots-rock melody made it a worldwide hit, the song was actually born from the internal disintegration of one of America's most successful bands. The Story Behind the "Rain"
While Fogerty maintained the song was about the band, many listeners of the era interpreted it as a reflection on the fading idealism of the 1960s or a metaphor for the Vietnam War. Chart Performance and Legacy