I honestly have no ideai have a space heater and will turn that on for him. gonna be low 40s tonight, i'm probably gonna be cold so he'll be chilly. woke him up last night and he was like "can a frog sleep here?" LOL then was very active. hoping around climbing..wanting to sit on my hand. so i think he's ok for now just wanting to stay in his cave cause it's a little cold in the tank. won't budge past 65.