Until this last week, I had 68 days of 100 degree or over (usually over) days. A friend who has raised chickens all her life said to give them tree shade because it's coolest, lots of water, a fan (I use a small 10" one outside the fence), and to damp down some ground. They've gotten along fine with that combination. Most of the time they aren't even panting. It's cooler under the trees than under any roof or shade-cloth and the chickens will dig into the damp earth, lie in it, and cool themselves off that way and/or get in front of the fan when needed. The fan does make a big difference here; there's been no breeze to speak of almost every day and the humidity has also been high most of the day.
Don't worry too much; just take some of the steps people are recommending and I'm sure your chickens will be fine.
Don't worry too much; just take some of the steps people are recommending and I'm sure your chickens will be fine.