Grand Theft Auto: The Trilogy — The Definitive Edition is full of strange changes. One of them is a new rain texture that makes its almost unplayable when its starts to pour. As always modders are first to fix the issue. New version of a Rain Fix mod is a must for the updated San Andreas.
Rain Fix by GTATrilogyMods let you choose the density: 50% or 35%.
You can also download a similar mod from the Jéssica Natália. This version fix the ripples in all games of The Trilogy: GTA 3, GTA: Vice City and GTA: San Andreas.