The higher the temp the higher humidity, that being said, what you want is constant temp,i.e (heated rod) so the humidity is constant. If the temperature is fluctuating the cooler steel will condense moisture out of the warmer air and corosion will occur. That is why the steel condenses moisture on it when you go from a cold place like outside into a warm room, it will not condense when you go from warm to cold.
If you use a constant temp and find your humidity is too high for your storage area your best bet is desicant dryers of some form or another, however you need to have some humidity in the air, if you remove too much you can end up with damaged wood finishes, or cracked stocks from too low a humidity level.
Just my two cents