I have a survival world with normal difficulty, no experimental features enabled. 5 or 6 Minecraft days ago there was a thunderstorm in my world. I went to sleep and the storm went away, but the rain remained.

When I went to sleep the next time, the rain still remained. I decided to restart the world and the rain went away, but it came back in the middle of the day.
Went to sleep again, still rain.

Restarted my world, rain gone. Only to come back 3 or 4 minutes later and not go away until I restart my world.
I haven't tried commands yet, because it is my long term survival world and I don't want to turn off achievements.