Thermal data were collected from 15 of 16 species of snakes found at the Mason Neck National Wildlife Refuge, Fairfax County, VA. Data recorded at each capture included the date, 24-hour military time, body temperature (BT), air temperature (AT), ground-surface temperature (ST), water temperature (WT) if in water, and the snake's activity (under cover, moving on land, basking, foraging, climbing, swimming, courting/mating). The purpose of this study was to determine the potential range of operating body temperature (OBT) of the individual species. The range of OBT is interpreted as the snake's operating temperature at its current environmental temperatures (ET), which can be used in comparisons with similar data from other North American regions, and represents the first such report from the Mid-Atlantic Region. The mean and ranges of BT, AT, ST, and WT are presented for the eight snakes with 20 or more records: Carphophis amoenus (n = 238), Coluber constrictor (204), Nerodia sipedon (67), Thamnophis sirtalis (55), Diadophis punctatus (54), Pantherophis alleghaniensis (43), Thamnophis sauritus (26), and Agkistrodon contortrix (24). New thermal records are reported for several of these species. The ranges of BT during activities are also reported. New temperature records are also reported for Virginia valeriae (n = 16 encounters), Storeria dekayi (12), Opheodrys aestivus (6), Lampropeltis calligaster (6), and Regina septemvittata (2).