I live in an area prone to flooding and although I have never had any really serious water issues I did have a bit of water in my basement one year, as a result the bulk of my emergency supplies are stored in various locations on the main level of my house allowing me complete climate control to help me get the most shelf life from my food stores.
As my house is located in a farming area my house was built with a cold storage room that has decent shelving and would allow ample room for my food stores, but as a cold storage room, it is off the basement, has a "vent" i guess it would be called to the outside and no means of allowing me any temperature/Humidity/Moisture control.
As a farming area we do get the occassional tornado touch down and are often under a tornado warning, as such it has started re-thinking my food storage locations and thinking I should start moving my Emergency foods (mainly Freeze Dried and Dehydrated Product) to the basement for storage but moisture/humidity/climate control concerns has me hesitant. Being a basement location, security is a slight concern for me as well as basement windows would seem to be an easier penetration point.
So I guess my question would be am I safer to keep my food stores on the upper floors of the house where I don't need to be concerned with flooding and enviromental issues affecting them, or would I be better to move my stores to the basement where they would be safer in the event of a tornado touch down, but prone to shortened shelf lifes due to lack of proper climate control?
I know we can't plan perfectly for everything, but hopefully I can find a balance between these two possible local enviromental emergencies.
DaScribbler
________________________
I hasve a bsmt cold room also, I keep much of our supplies there off the floor on high shelves
The first consideration is to ask what is the packaging of your emergency supplies? If it is in cans or mylar then you should be ok regardless of moisture/humidity so long as it doesn't get wet. Any container/packaging that provides a complete non permeable barrier to air and water vapor will be good. Temperature and light will be your major concerns.
JAB
Look into submersible or sealable plastic barrels for storing your supplies, you can get them also with moisture meters on them that will indicate moisture content of barrel. 
"We 'Prep.' to live after a downfall, Not just to survive."
Place a small exhaust fan at the basement end of the vent. You could also put a dehumidifier in the basement. Unless there is water constantly entering your basement the dehumidifier will dry it out. A dry basement is far more healthy and useful than a damp one.
I'm all for splitting the supplies and not keeping everything in one location. It wouldn't necessarily have to be an even split, but each storage place should contain items from each food group - ie veggies, protein, grains, etc. Having said that, my own storage situation is a little out of control now, far from perfect. I have a plan in place to make it better after I move sometime soon hopefully.
I think the previous posters gave you some good tips on how to make sure your food would keep in the cold room downstairs, however it might not hurt to keep some of it upstairs as well.
My next set of days off (the joys of being a working class smuck) I'm going to over haul my basement and move my emergency water supplies and maybe emergency solar lighting and solar powered radio equipment to the cold storage room. Temperature should have minimal effect on them (if water gets cold, good stuff 🙂 ) and who knows if an emp hits maybe I'll get lucky and the concrete/wood construction on the cold storage room just might save my solar powered equipment some grief (ya never know).
Then this winter if the water doesn't freeze it might be feasable to move my food stores in there as well.
It'll take some work to make it all fit, but with the available shelving it should work with a little modification 🙂
DaScribbler
________________________