"Red Rain" is the first track on Peter Gabriel's 1986 solo album So. In the USA, it reached #3 on Billboard magazine's Mainstream Rock Tracks chart. Stewart Copeland from The Police played the hi-hat for the rain-like background sound.
The song is a combination of several inspirations. The lyrics directly reference a recurring dream Gabriel was having where he swam through red water.
Earlier in his solo career, Gabriel had an idea for a movie, Mozo. In it, villagers were punished for their sins with a blood red rain. "Red Rain" was to be the theme song. This idea was eventually scrapped, although there was a mention of Mozo in the song "On the Air" (as well as in "Down the Dolce Vita," "Exposure," "Here Comes the Flood," and "That Voice Again") in Peter Gabriel (II).
Here are first the music video, and then the performance of "Red Rain" at the 1986 Amnesty International concert: