I have a ceramic heat emitter on a stand over one side of the enclosure. (When I first got him last year he had a bad burn from a heating pad, so I haven’t wanted to use one.) I had the hot side in the 90s for a while, but he seems content with the mid 80s and spends a lot of time on the cool side when the enclosure is at that temperature, so I try to keep it in the mid 80s now. It got colder than that this week, hence my temperature concern. I have it at 89 now and will make sure it is warm before I feed him.