Six weeks ago my wife brought home twenty baby chickens. After weeks of brutal construction, I have finally (mostly) finished the coop and he chickens are in it. We bought a prefab 10'x10 ' shed with a loft and converted it to a coop. I cut windows and placed 1/2" mesh over them. Of course, then it threatened to rain. I've got heavy plastic sheeting hooked over the windows when it rains. I installed a remote temperature sensor. My wife noticed the coop was getting warm 98) so I installed a box fan into one winow. Personally, I think 98 is probably nothing. I'm a little concerned though, that when I cover the windows for rain, like I did tonight, that the air might become toxic. That can't be right though, because I'll certainly have to have it sealed more in the winter. How cold and how hot can chickens get? What about chickens that are only about 5-6 weeks old? It's going to get into the 40's this week, will I need the heat lamp?