So it's going to be -32F by dawn on Monday here. And subzero daytime highs, lows in the -20's next 5 days.
Enough! I've put a 250 W infrared lamp in the coop, aimed at the perch from a couple of feet away. Went out and lookedat 1:15 am, it was -23 F outside but +7 F inside. Chickens were lined up right in front of the lamp, faceing towards it... I'd say they like it.
I was away for a couple of days, and it went from + 20's to -20's from Friday to Sunday. I've got an automatic pop door... When the weather is subzero, the battery doesn't have the umph to open the door, apparently. While I was checking the coop Sunday afternoon, I saw a large bird fly onto the outdoor perch. Looking out the door, it was a poor dorking hen who had spent the previous night, and most of the next day outside- With no feeder, and no water except what she might get by eating snow. I opened the pop door and she went inside. Her comb was mostly white from frost bite, but she didn't appear to be too distressed, just very hungry.