So, from this thread:

http://mlpforums.com/topic/30969-can-it-rain-in-cloudsdale/#entry718275

I have seen that in fact, no it is unlikely it can rain in cloudsdale (but they can make tornadoes ).

I guess this is kind of a shame for them, and probably why you don't see many plants in clouds dale either

It must be great to be in the sun all the time I guess they have to be as it must be cold in the sky if it's anything like the world we live in.

Otherwise they would all freeze to death, in fact I wonder if they have season's in clouds dale? I'm guessing they must have as the weather they experience on the ground must have some sort of an effect on cloudsdale!

(this is my first real blog post please let me know how im doing/how to improve )

Happy Plant