The natural environment of Cephalotus follicularis is a meso-mediterranean type climate of warm summers and cool winters.
Optimum growth occurs at around 74F during the day, combined with a cool night temperature of around 56F. I have found that Cephalotus will survive and grow in a wide range of conditions. Too hot during the day (above 88F) is a problem if the humidity is low and it is in a terrarium in full sun, as they dislike high compost temperatures.
I have also found that it can take quite a lot of cold.
Here in the UK we occasionally get a few days down to 25F at night, hovering at freezing to 32F during the day, and my plants have survived this with no additional heat as long as the soil is not too wet and the light levels are adequate. Even if the top growth is damaged by frost and lost, new growth from any remaining roots does occur when the plants start growing in Spring.
I try to maintain my plants at around 52-58F during the winter days and growth does slow or stop. Dormancy is not strictly necessary for this plant and growth can be maintained all year round at daytime temperatures of 68F and above.