Re: Temp/Humidity for storage
you need to keep your powders someplace cooler than this, and the primers shouldn't be exposed to this sort of humidity. The temperature variation won't do them any good, either, but the humidity is a real problem. Some sort of airtight storage (GI Ammo cans will work fine, so long as the gasket is in good shape) is viable here. As for the powders, temperature variations are a problem, and extreme heat is a real killer for them, and will cause degradation and breakdown over time. An unopened can or keg should be airtight, but I wouldn't totally count on that, either. Problem here is, powder's hygroscopic; it absorbs moisture. It will do this out of humid air, just as it will actual water in contact with it. Again, it'll break it down over time, and will immediately cause drastic differences in performance when you load. Not a good thing, either way.
If at all possible, powder should be kept in a comfortable environment, such as inside the house. A friend of mine used to keep his powders not just in his reloading room, but in a refrigerator. This was a defunct fridge he picked up for free somewhere, not plugged in or running. But the extra insulation and a near airtight seal made for an ideal storage place.
Hope this helps,