[Exhibitman]

By the coast in Cali, high moisture, so high and corrosive that there are special construction guidelines for things like flashings and waterproofing materials. What the OP should do (we all should) is get some commercial silica dessicant packets and seed them throughout storage bins and boxes. That should help mitigate moisture in the boxes especially. Thankfully, I more or less live in a freakin' desert, so I've never had an issue, but I still keep dessicant packets in my safe deposit box and other storage. Cedar blocks too, to ward off any moths or other pests.