im out in the open desert in arizona. mine stay out year round in their runs. I have 70% shade cloth for them over the top of some of the run so they can have the choice of shade or sun. Also I keep shallow water pans filled daily so if they choose to go play around in the water to cool down they can.
I hose my bo's off in really hot weather (along with their coop). They hate it but they stop panting once they are wet. Also, I will let them into the yard so they can find more shade and bury themselves under my plants. We had weather over 110 her in southern california in recent weeks and they are fine.