I live in northern CA and are temps get down to about 15 degrees in the cold part of winter and my Seramas do just fine in there little coops . just my two cents on the subject .
pullet on left was RES champ of show in Reno Nevada 2012 one on right is her little sis have not showed her as of yet she will be going to Stockton Ca at the end of this month to see what she can do .