i second grz's keop recommendation. Kelp will help!!
i live in the great white north and this year taking alot of kelp has absolutely helped my core body temperature. i am thin and lose heat rapidly, so kelp has been a big help for me.
i take 1 or 2 tablespoons a day. its a whole food so i don't really worry about overdoing it. it feel great to me. i recommend the "frontier" brand, the "now" brand tastes awful!