Reload in the gargage. Store your powder and primers in a big tub that you can store in the climate controlled house. Not having a toddler get into your stuff is priceless.
As far as climate controlled goes, heat and humidity are the ones that worry me. In the mild Pacific Northwest I have no problem storing components in an non-climate controlled garage since Washingtonians don't understand the concept of humidity without precipitation it was fine for me. In a different climate then I would store powder and primers in a different manner.