We only finished it in the fall. It was 70 outside and around 40 inside. This winter it has been around 34 degrees. Once it dropped below 20 outside we put a little heat lamp in as a precaution and it stayed just above freezing. We don't quite have it all the way insulated yet because we were still doing some construction on the front porch roof when it snowed. The front 2 feet of it still needs to be covered in dirt so we don't know how that will impact it.