I've lived in central VA for 35 years now. I just keep a coat of 3n1 oil (for many years) or Mobil 1 oil (the last 10 or 12 years) on the surfaces and so far, no rust.
My guns were stored in the attic (hot/humid all summer, cold/humid in the winter) for decades. I remember pulling some of the older rifles out the soft cases (yeah, like you put your shotgun in when you go hunting) that had been oiled up and stored away 8 years before. No rust on any of them. These were parkerized rifles (03's, M1917s) but even the sporterized M1917s that were blued were not rusted.
How humid in the winter? I've gone out to the garage and found moisture condensed on the cars, tool boxes, etc. after a temperature change. A time or two I thought I'd had a roof leak till I got to checking and found the surfaces looked/felt like fog on a windshield that needed to be defrosted.
As they say, your mileage will vary, but a thorough cleaning and wipe down afterwards with an oily rag/cloth does wonders when done right. And, after you wipe it down, you don't touch any metal surfaces while putting it in the storage location.
