I'm in MN and in the middle of a cold snap. Today, we've had a high of -4, and it got down to -15 last night. It's supposed to dip down to -15 again tonight, with a high of 2 tomorrow, then H10/L -10 on Wed. All of my ladies seemed fine this morning, and although i initially wasn't going to let them into their run today, i decided open to pop door to let them decide. They spent most of the day outside. I checked over their combs this morning, and didn't notice anything wrong, but this afternoon i noticed that my gold star looks to have the beginnings of frost bite. I've attached a picture, you'll see that front prongs of her comb are starting to turn purple (not black). This is frost bite, right? My question is - with the temps going down to -15 again tonight, should i bring her/all of them in to prevent this from getting worse? Will it cause problems if i bring them back out when the temperature gets to around 0? (it's supposed to still be -15 until 9AM, not warming to 0 until 2PM) Should i just bring in the affected one along with a buddy (i'm thinking our California White as she has the next largest comb) or all of them? We have a large 3' x 4' dog crate and red heat lamp in our garage that we used as their brooder this summer. I'm thinking about bringing them in there for the worst of this cold snap. I do not want to run the heat lamp out to the coop. This is their first winter and I do not want to coddle them to the point that they cannot handle the cold on their own, but with these lows and the threat of frostbite, i'm feeling uneasy about leaving them on their own tonight. Some additional details (I'm really looking for a short-term answer to my question above, but feel free to provide any insight you may have about this set-up long term): I do not intend to heat the coop, at least not regularly. I may look into a ceramic heater or something that I know is safe for the handful of times a year it gets below -10, but i'm very hesitant. We're in the Twin Cities metro area so we don't see quite as extreme temps as they get further north. I honestly didn't think they would need it after all of that I've read. I'm certainly not planning to keep them at a consistent 40, or even 20 degrees like i've seen others doing. I do know that ventilation is key for minimal moisture, and that it's important to keep them free from drafts. The coop is about 8'L x 5'W x 7'H. It has thin insulation (that foil bubble-wrap type), on the walls and doubled at the ceiling. There are two large (2' x 2') cut out windows with chicken wire and tight fitting plywood flaps to close them up. We have the one closest to the roost blocked up by card board, but do open the other one up most days. We also have vents at the top, two on the long wall and one on each short wall. I really thought this was plenty of ventilation, but now i'm wondering if this comb issue is an indication that it's not. I do keep their heated waterer in the coop, this goes off on a timer during the middle of the night, then comes on around 5 so it's thawed before they're up. They roost on 2 x 4's on the wide side, so they can sit on their feet to keep them warm. Their run is covered, and has wind blocks up so they can huddle out of the wind. They choose to go out to the run every day, and do free range for at least a couple hours day (well, some do - they're not so excited about the snow covered yard right now). I have 2 x Barred Rocks, 1 x RIR, 1 x Golden Comet (pictured) and 1 x California White. Thanks for any advice in advance!