For a number of reasons, I'm thinking about storing ammo in other locations than just my bedroom closet. The attic is one choice, but since the floor is insulated and not the roof, the temperature swings are major in both the summer and the winter. I also thought about putting a couple of battle packs and a couple hundred rounds of handgun and/or shotgun in the truck in case I had to bug out fast and couldn't grab enough.

That said, is there any definitive info out there dealing with the affect of temperature (and temperature changes) on ammo?

The info I've always heard is to keep ammo in a COOL DRY place.  And no temperature fluctuations.. up/down/up/down.