I've gone in early August, early December, and early May. August and May were both hot, but the humidity in August definitely made it worse. I didn't mind as much, we have hot & humid summers where I am in the midwest, so I was ready for it. I just drank tons of water, wore lightweight moisture wicking clothes, and made to sure to go into shops and do some indoor activities to cool down every once in a while. And that was all without taking mid-day breaks. I'm on the go from rope drop to park close and I managed just fine. Never got overheated or dehydrated (which has happened at home before). I would totally go again in August, preferably late August for the lower crowds. It'll be hot & humid but definitely manageable.