Rain is indicative of good and blessing, and of mercy bestowed by prominent people, as well as abundance and great benefits from trade. If the rain falls on a certain house it is indicative of harm, because Allah says:
“Because of the inconvenience of rain.”
Rain may also be indicative of worries, because Allah says: “And rained down on them stones of baked clay.”
The word ma’ (water) is that which is indicative of relief, because Allah says: “And We send down blessed water (rain) from the sky.”
What matters in this regard is what the dreamer understands in his dream. So if he sees a lot of harmful rain, then it is bad.