Although you encounter more humidity on a daily basis than I do, I have never had (nor do I know of anyone who has had) any problems with storing planes in a garage or any other space that isn't climate controlled. Just so long as they dont' get rained on, or aren't exposed directly to the elements, you will be fine. I keep mine in my trailer, and have done so for over 3 years now. I've never had a problem related to storage.