It is sort of night and day even in a plains biome though it is not raining sometime the rain does not show rain until you save and quit too and go into the world again.

I was playing in my world and it was day but it looked half night time.

I was playing with freinds and one said that it was raining and me and one other freinds said we could not so I saved and quitted and rejoined and it was perfectly fine.

 

(This randomly happens from time to time.)