Our one day of hot summer weather is over here in the Pacific Northwest, so far, anyway. At my place it reached the ninety degree mark for a bit during the middle of the day Saturday. The chickens and all my other animals did fine with frequent watering and basically just leaving them undisturbed 'til evening. No walk for my dog, instead she got a bone and a huge dish of cold water. Spoiled Kitty joined me in the comfort of several strategically positioned fans. I caught up on reading; he lounged.
It's really important to have a shady place for the chickens to congregate during a heat wave, no challenge when you're in a forest, but otherwise something temporary probably needs to be set up. Possibly just a tarp anchored between fence posts or something could be effective. Don't handle them or feed them much until it cools off later in the day, it'll just make them hotter.
Guess we're pretty spoiled here, as, in other places its been at least approaching, if not exceeding, the 100 degree mark. Gotta hand it to all those people who are living in that kind of heat-if that's you, you're special. The heat just wipes me out. You've also probably figured out your own means of keeping your chickens and other animals cool and at least somewhat comfortable.