I have kept most of my guns in an unheated pole barn shop with a concrete floor inside a large antique Mosler (I think that's the name) safe for several years now. It is a big safe, weighs about 5000 lbs. I'm told, and has walls and double doors about 10" thick. I drilled through the floor when it was given to me and ran the cord inside for a Goldenrod. I have seen the outside of the safe literally dripping water off it from condensation, but upon opening the doors the contents are always warm and dry with never any hint of condensation or rust. The Goldenrod is an amazing little piece of work, and the post by Ducky's Dad helps me understand the effectiveness of it. I wouldn't worry about the temps, and I can't imagine you could have humidity as high as I do down heah'. We joke that if you don't like the weather just wait a few minutes and it will change.
Like others have suggested, I'd watch the contents closely for a few months just to make sure your equipment is all working as it should, but I don't think you'll have any problem.
Stan
