It's hot here too, and I notice depending on the day, there's usually a handful that are standing on the roost at night, fluffing out their wings and/or panting, - but not all of them, - and on the nights when I would go back to check later, they have all been settled in as the night starts to cool off a bit.
I have three large HWC windows on the three main sides of the coop, as well as a screen door. If it were hot enough, I could weigh my risks and choose to only close the screen door at first, and wait a few more hours to lock it up tight until cooler, darker nightfall.
Throughout the hottest days, I bring them fresh ice to chill their waterers and make sure they are all topped up. Remember, it's good to dump the water and refill the whole thing fresh when adding ice, because the water may have already become warm, which shoots you in the foot. I can also put a frozen gallon water bottle in there in the late afternoon, wrapped in a towel just to help from it sweating. But I always step right in there to check on them, and the fact is, it's not any hotter inside their coop than outside, and on hot, sunny mornings, it actually feels cooler! As long as you are doing everything you can reasonably do to set them up comfortably and keep them hydrated, the panting and fluffing may just be a normal, unavoidable response to the stupid summer heat.
