I use a mister system for mine, and it is helpful, but I live in California where it is not too humid. I have seen a lot of posts say it is not helpful when there is high humidity. I have found that deep dark shade is most helpful, along with moist soil to dig down into. Try spraying the ground with a hose several times a day. Others have found a shallow pool helpful for the hens to stand in, although mine won't do that. Frozen water bottles can cool the areas around them. Keep them hydrated with greens and treats like watermelon and blueberries that contain a lot of water. Ice cubes in the water can help. I will be honest, when we hit triple digits, mine come in the house, in collapsible dog crates, until evening cooldown. I have a small flock, though.