You can build a comfortable outhouse seat from simple materials during cold weather.
I have a camp in northern Ontario, 200 miles north of Sault Saint Marie — where temps hover at times in the -40 degrees Fahrenheit range and even colder — and I have a suggestion for a really comfortable outhouse seat, especially for winter. Take a piece of styrofoam or bead board — not the rigid or hard form — preferably an inch thick. Our first one was cut from the side of a foam cooler. Cut out a match for the existing hole in the board used for a seat, and fasten it down. Believe me, a trip to the outhouse on a -40 degrees Fahrenheit morning tums into a comfortable sit, as the styrofoam reflects your body heat.