If you have not used heat yet, don't. Your chickens acclimate by growing extra feathers and down. Just like other animals grow a thicker coat of hair for the winter. I live in MN, and the temps get down into the teens to twenty below, sometimes it will bottom out in the -30's. (Thankfully not for too many days in a row!) My chickens have survived it. Consistent temperatures, even if they are cold, are less stressful for your chickens to deal with. Try this: put on all your outdoor gear - coat, hat, mittens, scarf, snow pants and boots. Go outside for an hour. Half an hour if it's really cold. Now, come back in and leave your gear on in your nice warm house. Leave it on for at least an hour. Your chickens don't get to take off their coats. They are not feathered little humans. Another thing to think about - all the little songbirds that survive the winter without shelter or heat. They are equipped to do so, just like your chickens.am I correct that none of you in these cold temperatures are running heat lamps in the coop itself? I am also in New Hampshire and we're headed to below 0 temps tomorrow and tomorrow night but I'm just wondering if I should put a little extra heat in there for them on these evenings where it gets super cold? My flock have not had heat since they were checks in the spring as I wanted them to acclimate to the NH winters. I just don't know how cold is too cold. Thanks all!