Rain Falls Through Solid Blocks

What I expected to happen was...:
Rain does not normally go through solid blocks.

What actually happened was...:
Rain was going through solid blocks (house and underground). It effects all elevations, but seems to fall through random blocks. Could be based off of the number of consecutive solid blocks above it as it is less prevalent, but still existant, near bedrock.

Steps to Reproduce:
1. Turn on rain.
2. Go underground.
3. Report bug.