FWIW, I keep everything inside; fuel, dope, kits, planes. It's always between humid and wet in the Houston area; really warm in the Summer and quite cool in Fall/Winter (sometimes really "windy", too). If our garage were insulated and temp-controlled, that would be preferable, but it isn't.
Yes, I know our insurance agent would have kittens if he knew of all the stuff I store inside.