Depends on the humidity level in your coop. I have read that they are fine down to about minus 30 F if well ventilated. I'd check for any sign of moisture or condensation in the coop. They can get frostbbitten at 32 F in a humid environment.
This is our first year with chickens. This morning it's 23 degrees F. They already have Vaseline on their combs, trying to be on the safe side. I don't know of a downside to it. We have plenty of ventilation, no bad odors in the coop, and no condensation. But it does get pretty cold in there. I'm considering closing off part of the ventilation, and keeping an eye on it. Colder weather is on the way. Ed
