Most research on the winter ecology of temperate-zone snakes is restricted to aspects of hibernation, because that is largely how snakes spend the winter. At lower latitudes, however, the same snake species may be active during winter, although why they are active and how much individuals vary in activity is unknown. We used radio-telemetry data from three winters to document winter movements of 30 rat snakes (Elaphe obsoleta) in Texas. Snakes moved in all months, although there was substantial individual and gender-based variation. Consistent with active snakes foraging, monthly variation in movement was associated with availability of ‘thermal windows’ that would allow digestion of a meal. Females were more active than males, suggesting increased foraging demands. Individual activity in winter was positively correlated with activity the previous summer, particular among females. This may reflect enduring effects of variation in reproductive costs, or intrinsic variation in activity of individual snakes. Variation in activity was associated with differences in habitat use but not thermoregulation, although the data available to assess thermoregulation allowed limited resolution. Climate warming will increase the thermal opportunities for winter foraging, which will have implications both for snakes and their prey.