The humidity in a gun safe should never get over 50%. If you live in a humid environment it may be that you’ll also want to add a gun safe dehumidifier that requires still more internal space.
Of course, you won’t need a safe with a 48-rifle capacity if you have only a few long guns, but do consider what else you’ll be storing inside and whether you’ll need to add a gun safe dehumidifier so you won’t regret buying a gun safe that really could use some extra space inside.