Like RebelHog, where I live it is hot and humid or cold and humid (it is texas - don't like the weather, wait 15 minutes!). Most of the time you can swing a stick through the air and it will rain.

So, I use damp-rid and I also have ade it a habit to have a mandintory gun cleaning day once a month whether I have been hunting/shooting or not.

Take the dehumidification ideas in this thread seriously and you should not have an issue with the safe in the basement unless your area is prone to flooding.