Can magic or devils cause rain to fall or prevent it, or is God alone capable of that?

Rain cannot be brought down by magic, nor does Satan have the power to do so. Allah alone is the One who creates the clouds and sends down the rain, as He, the Almighty, says: "And He it is who sends down the relieving rain after they had despaired and spreads His mercy. And He is the Protector, the Praiseworthy" [Ash-Shura: 28], and "Indeed, Allah [alone] has knowledge of the Hour and sends down the rain" [Luqman: 34]. The sending down of rain is among the keys of the unseen, which no one knows but Allah.