Our new chicks (20) were in a plastic 45 gallon tote up until today. We couldn't take the smell inside any longer. I built them a brooder that's 6 x 4 ft and 24 inches tall. They were moved into it today into a side room off a small pole building in my back yard. I cut 1 x 2 ft vents into one side, but it was still pretty hot here in Rolla, MO. Mid 90's I guess. I didn't have a thermometer in there until I made a trip to Wal-mart earlier. A couple of my Cornish x chicks were panting pretty hard. I mounted a box fan and cooled it off pretty quick. Now I'm worried about tomorrow afternoon. So I guess my question really is, how hot is too hot for baby chicks?