Hi, I too live in Florida the east coast 300 feet from the intercoastal and I can hear the ocean from my house. Probably less than a mile away. It really does not get that hot in the garage, maybe upper 80s. I would contact CE Safes. Give him a call he is very knowledgeable about safes and is very happy to talk to anyone about them, at length so be prepared. He sells real safes not security fire safes like you see in many of the big box stores. Made of real steel measured not by gauge but in fraction of inches. He even has safes custom built if that fits your needs or he sells Fort Knox, Grufunder and several other brands. He has one store in Deerfield Beach and another in Fort Myers I believe. I have alot of tools, a fairly expensive Italian Sports car which have been stored in my garage for twelve years, no rust issues anywhere. I had an AC drop run to my garage that I can open when I work out there. The dehumidifiers, as you might know, are primarily installed to help absorb the moisture which is present in the fireproof drywall which is installed in the walls and door of the safe to give the safe a fire rating, it is very moist not for moisture in the surrounding open air. Keep you firearms in gun socks and take them out now and then, inspect and care for them as needed and you will not have a problem. Of course bolt the safe down with a minimum of three bolt into the concrete.