Jacksons can do well with even lower temps than 60 to 65. Most of my Jacksons spend the winter outside and can handle mid 40s without any problems. Our winters days heat up to 68 to 70 on average, so that may be why they can handle the temps in the 40's. I do make sure that the Jacksons cages get the first rays of sunlight in the morning so they can warm up.