I'm pretty sure that MRE's would be ok for a summer just about anywhere in the USA, even Death Valley. According to this chart: MRE longevity , they would be good for 5 months at 110*F. I'm betting that it is the average temperature that matters, not the extreme. Same with canned foods like Dinty Moore (one of my favorites) or Spam. What worries me are repeated freeze/thaw cycles. I've noticed that both taste and texture become seriously degraded after a hard freeze.