Hmm, i had my first ball python in a similar situation for a while. I live in the south so its hot here, but college dorms stay cold (we don't have to pay for electricity, haha) so it easily stayed about 70 degrees F inside. I was using a 10 gallon tank because he was a hatchling and with a lamp on all the time and tin foil staying on the top of the aquarium i think it stayed around 55% humidty with daily misting