What is your setup?
I'd have put them out already. They can and should be exposed to the soil they will live on by about 7 days old.
If it is that hot, you will need to provide lots of shade and cool water. Heat will kill a chicken much easier than cold.
Some, myself included, provide a very large piece of ice in a shallow plastic bin in a shady location. The chickens will wallow in it and drink the cold water to help keep cool. I also cut up fruit into small pieces and freeze it then break up the chunks and feed them.