Actually all of my first chicks were out without any heat by 5.5 weeks, temps in the teens, with snow. It snowed the second night they were out, on April 1st, and we had snow up until June 6th.. Scout was just a little younger when he was out there in -4 degrees, but that's NOT something I would normally advocate. He did it, did great, and didn't even have any one to cuddle with, but I would feel terrible if someone said, "Well Blooie says put 'em out in negative temps" and then something happened. If yours are still using the pad, then they are telling you they still appreciate that little bit of extra heat, so I'd listen to them instead of an old lady in Wyoming!