I have my world that I've been using in each new snapshot with no problems. Today, however, when I logged in, I went mining and my world started raining. That wasn't a problem until I got into the caves, and the rain was clipping through all the blocks above it and falling into my cave system- even in places where I haven't loaded/explored yet. I dug up to see if it was just through one block, but it seems to be clipping down to about level 11 (where I was mining). It's not everywhere, it's only in groups of blocks.