My last broody was up and down off her nest, eating drinking, sometimes letting them go stone cold and yet they all hatched fine. A friend in Louisiana regularly hatches great clutches when it's over 100 every day and over 100% humidity. She laughs when I talk about keeping eggs at 50% humidity and 100 degrees, she says that's practically airconditioned by her standards. She has very successfully hatched eggs by putting them on an egg turner sitting in a cardboard box on her porch with no incubator or hen involved. BUT! If my incubator varies more than a few degrees or the humidity slide just a little to much then it's a crappy hatch. Go figure.