It never rains in sunny Pandora (Avatar) - but it should

I just realized that despite the rain-foresty environment of Pandora, characterized by a) lush, BIG vegetation; b) waterfalls dripping off of floating mountains [see above]; c) natives wearing hardly any clothes (yes, the Na'Vi were nearly naked); and d) a lot of water in the ecosystem (remember the river Jake jumped into to escape the Thanator) -- that I don't recall a single scene in which it was actually raining. Now, arguably this would have been hard to do in the outdoor action scenes and look realistic, even though Avatar's CGI was pretty amazing -- but it wouldn't have been hard to do, like when the drivers are in the mobile lab, they could have heard raindrops
pounding on the outside of the lab and water pouring down the windows one night. Now, it could also be covered up by saying that this region of Pandora has wet and dry seasons, and that the action only took place during the dry season (mining operations and logging could get very bogged down in heavy rains, so this is plausible), but there was never any allusion to that type of seasonality.

Also, it was very sunny a lot of the time. That's not very realistic in a rainy and foggy and cloudy and misty rain forest environment.

So this could be an oversight in Cameron's vision. I did a little Google searching and there doesn't appear to be any mention or discussion of this issue. Maybe I should email him.