LLM Driven Rain addon
Flowing Fluids mod by Traben (Required)

Simply use /subtlerain and a how many water source blocks you want to gen on land above sea level in 32 chunk radius around player while its raining
Example
/subtlerain 6 means 6 water gen every 20 ticks in a 32 chunk radius
/subtlerain 4096 god help your device...
thanks to HanaeYu for the 1.0.1 increase update idea
Use it how you feel like full permission to do whatever to it just dont harm people or property with it. nothing illegal.
You may not multiplayer host this mod from a california based server.