Imbrēs • Imber ( rain, a storm, (poetic) a stormcloud )
Caelō • Caelum ( vault of heaven, sky, atmosphere, climate, weather ) •
"Rains" fall from the sky.
The plural of rain in English sounds wrong to me. However, I'm German and not a native speaker. This seems to me like a technical translation, that is structurally equivalent but not idiomatically correct.