Layers of shade! I live in a climate like yours and I can't emphasize how important shade is to survival in our kind of heat. In the best possible situation your coop should be completely in the shade where the sun's rays never hit it. If your coop is going to be directly exposed to the sun consider constructing layers of shade, which are more effective than a single layer. I use shade cloth, which allows for movement of air and two layers of it limit most sunlight from entering the coop. You can see what I did on my byc page.