I live in the high-desert country of northern Nevada. My reloading "shop" is a dusty 10x12 wooden garden shed which is insulated for the times when I use heat or air-conditioning. The summer temperatures in the shed reach levels where my regular 50/50 alox type lube literally runs off cast bullets which are not yet loaded into cases....well over 110 degrees, since outside air temps will reach that figure sometimes.
HOWEVER: Not long ago, I took a large number of rounds to the range, which had been loaded in 2002 or earlier, and stored in that shed ever since. Total number was around 800 rounds, I believe. Included in the mix was a number of others which had been stored in my shooting van for several years. All of these rounds used the 50/50 alox(Javelina brand) lubricant. EVERY round fired normally, and those I chronographed were still performing just as if they were freshly loaded.
I confess that I didn't know what to expect from all this older ammo, given the heat to which it had been exposed, and I'll also admit to a great feeling of relief in finding that I don't have to worry too much if I leave ammunition for a year or two after loading. Nowadays, in summer I tend to leave the a/c on at low settings to keep the inside temperature around ...oh, maybe ninety degrees or thereabouts. I anticipate no trouble in the future from heat-exposed rounds.