My area is not especially humid most of the time, but it does get hot.I have both hatchery 'American' and English Orpingtons. I wouldn't say they *thrived* over the summer with weeks and weeks of 100+ (quite often in the hundred-teens) temperatures, but with minimal efforts (misting the run at peak heat, electrolytes in water, things like that) I did not lose a singe one to heat. They don't love it, but with shade and sympathy watermelon they can handle it. The hatchery birds handled it better than than the super fluffy and heavy English ones, but all survived.
Hopefully someone has more experience on the humidity side.