It is amazing how well the chickens adapt to cold weather. I think of chickens as cousins of the passerines (perching birds > song birds) and how well they adapt. If a little tiny chickadee can survive, of course our chickens can with wind protection!
http://www.kittycooks.com/how-to-winterize-your-chicken-coop.html
http://www.kittycooks.com/how-to-winterize-your-chicken-coop.html