Basically it rains all the time.
Just because there are clouds in the sky doesn't mean that it should rain.
The sky should be able to become fully overcast without raining and only rain occasionally.
The rain effect also has a really obvious & visible loop to the animation every 1 second.
Also the rain has no depth meaning it only rains in front of you in a flat sheet around the player and nowhere else. (heavy rain should reduce visibility over distance)
The rain also follows you into buildings which are larger than the area of the rain effect around the player :-s