I've seen this on a couple servers I've been on, and it's started happening on my own server as well.
What happens is, it'll start raining, and everyone hates the rain, so someone will use some sort of rain stopper (e.g. Reliquary's Sand Shot, Forestry's Rainmaker + Dissipation Charge, Thaumic Tinkerer's Crystal of Climate Sunlight). Then literally 1 minute later it will start raining again.
I've seen it rain 10 times in one day. We've found that sleeping helps relieve the rain for a bit.
Does anybody know anything about this?
I've ruled out the following:
* Somebody using Thaumcraft. This started happening on our server long before anybody got into thaumcraft.
* Bees. Again, started happening long before anybody got into bees.
* Rainmaker. I was the first one to build a rainmaker on the server, and it was to stop the frequent rain.
* Griefing/excessive trolling/dickery. This happens when I'm the only one online, and it's a private server where everyone complains about the rain, so nobody would intentionally make it rain to the point of excess like this. If anything, I'm probably the biggest troll on the server.