The Nature's Head can be used in all climates. The composting process in the solids bin will stop during very cold weather when the material reaches 32° F (0° C). The biological process of composting decomposes organic material under aerobic (oxygen is required) conditions, promoting the growth of aeobic bacteria. These bacteria heat up the composting material as they work.
However, in colder weather, the microbes are unable to keep the compost warm enough to keep the decomposition going. In cold weather, microbes will not die, but simply go into hibernation. Composting works best starting at 55°F and pathogens are killed at 120° F.
If your toilet is installed in a place that will be unoccupied during the cold season, it is not necessary to empty the solids chamber, as decomposition will start again when the chamber starts to warm again in the spring.