At its southwestern range limit in southeastern Arizona, the Desert Box Turtle Terrapene ornata luteola, takes refuge in subterranean mammal burrows, primarily those of the Kangaroo Rat Dipodomys spectabilis, from November through June. I inferred temporal and physiological characteristics of turtles in burrows from temperatures collected with miniature data loggers buried in the soil and attached to turtles from August 2001 through June 2003. In the fall, entrance into hibernation varied among individual turtles and between years from 18 October to 6 December. Mean daily body temperatures at the beginning of hibernation were about 14–18°C. From December through February, body temperatures averaged about 9°C and were slightly less than and highly correlated with the 30-cm soil temperature. By April, body temperatures of turtles approached levels exhibited by surface-active turtles (minimum approximately 18°C for moving turtles) but turtles did not emerge from burrows until the summer monsoons began about three months later. Thus, the five-month hibernation period of T. o. luteola was contiguous with a three-month estivation period for a total annual period of subterranean refuge of about eight months. Except for extending into warm months, the annual inactive period of T. o. luteola in southeastern Arizona was not remarkably different from that in other parts of the species' range.