This never happened in the previous snapshots that I have played before. When it started raining, I went inside my house that I've built in Creative Mode only to find out that it was raining inside. (This is the same for the pig's house and the horses' stable) I don't what could be the case as I have recently started playing Minecraft: Java Edition recently (March 2020).
Below are screenshots of the issue that I have.
Environment
Java version 8 Update 251 on Windows 10.
Thank you for your report!
We're actually already tracking this issue in MC-179845, so I've resolved and linked this ticket as a duplicate.
That ticket has already been resolved as Fixed. The fix will arrive in the next version or is already included in the latest development version of the game, you can check the Fix Version/s field in that ticket to learn more.
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