Oh I have experience with gunite in 100+ weather and almost no humidity. We shot in the Mojave Desert. I set up a sprinkler and left it being watered lightly for hours at a time for the first week. After that we watered it morning and night and occasionally at lunch if it was screaming hot and when wasn't it screaming hot here? Finally we watered it daily in the afternoon/evening.

FWIW we had no cracking and our inspectors said it was one of the nicest gunite jobs he'd ever seen. It really was a good job, we were only 1/8" out over the entire pool!
Jo