What was their last living situation? Were they in an unheated coop? If they have been living in an unheated coop all winter they will most likely be fine. Although it is unsubstantiated, I think they would have problems going from 65 to 30, but will be OK if they have had time to acclimate.
Mine have been fine all winter in their insulated, but unheated coop.
Try to find out what the night time temps have been where they are coming from and what type housing they are use to. If similar to yours, should be ok. Post pictures when you can! What kind of chickens are they?