I've noticed my chickens are hiding from the sun. Would they enjoy a puddle of water? I could easily dig a small area in my garden and add 2" of water ( soil is heavy with 75% clay.) Water will stay in the hole for 5- 10 minutes.
My chickens love puddles of water. I have large pans in their yards that I keep filled with cool water and they have shade. I also spray water under their shade tables to make it damp and cooler for them. They like to wade in the pans of water. In the bottom picture I used a plastic storage box that goes under a bed. Also I have a sprinkler I turn on for awhile in the afternoon when it is the hottest and the chicken get under it and scratch around. I live in Florida and it has been in the 90's here already for the last couple of months.