I live in sw idaho. I added a turkin to my flock this spring, but now that it's getting cold, I'm getting concerned about her. I have a multi-breed flock with 3 bantums, and 4 full-sized birds. Their coop is 4 ft high, 4 ft wide & about 3 ft long. My access is one wall. We have a vent on one wall & a chicken-sized door on the other going to an enclosed run. The coop isn't insulated & i don't have a heater. They have free range outside, but i lock them in at night. Its gotten down to the teens at night before, and our typical day temperatures run 20s to 40s. Is there anything i should do to help her? I've never got frost-bit combs, but mine don't have big combs. I've not had issues with the cochin, polish, wydonott, or black star (black sex-link). We have gotten up to 8" of snow at a time. I try to provide them a road to the water, which is in a heated water bowl next to the house. I also usually but straw in the coop & make a little windbreak outside the cage, since our winds are vicious.
Treat your NN the same as you should all your flock. Feed them well, supply fresh clean water at least twice daily and you will find the NN is like as hardy as any other bird you have and more hardy than most.
All chickens need fresh air but none of them need serious drafts and snow or rain blowing in on them and their bedding.
Under really harsh conditions, I would bet the NN would be the last bird standing but I hope you can make their lives very comfortable.
TURK