We're forecast for a few nights near 0 degF, in the next few days. Not all that unusual for us, but after a few abnormally warm years in a row, it's by far the coldest my flock has experienced. The flock: 2 year olds: Easter Egger, Plymouth Barred Rock 4 month olds: Golden Lace Wyandote, Asian Black Unheated and uninsulated coop, although it is painted a dark color to pick up some solar heating, if the sun happens to come out. Well ventilated at roof, but should be no drafts on the roosting birds. Should I be concerned, with these birds not being very used to this kind of cold? What should I watch for? Should I run an extension cord and put a heat lamp in the coop for these cold overnights, or let them tough it out? Google tells me chickens are generally fine down to -20C (-4F), and we are forecast for 1F dry bulb with -8F windchill, so that's comforting. But this flock has been living the easy life with winter temperatures barely below freezing so far this year.