The most important thing with ammo is storing it in a cool, dry, place. With that said, ammo is amazingly resilient. I've shot rimfire ammo that's been left outside (in the rain and snow) for weeks and it still functioned just fine.

Anyway, I store my ammunition in ammo cans or dry-boxes. Make sure the seals are good on the can/box, toss in a desiccant pack with it, and the stuff will outlive you no problem.