We examined the relationship between insolation, climate, and hibernacula of black-tailed (Crotalus molossus), Great Basin (Crotalus lutosus), and western diamondback (Crotalus atrox) rattlesnakes at 4 sites in Arizona, Nevada, and Utah, Hibernacula were located through a combination of visual searches and radio telemetry from 1995 to 2003. We used global information systems to calculate insolation and compared hibernaculum insolation values with random points representing available insolation of the surrounding habitat. Insolation reflects soil temperatures, and we predicted that hibernacula in cool climates, at high elevations, and at high latitudes would have higher insolation relative to their surroundings, while hibernacula in warmer climates would not differ from their surroundings in insolation. Coolest temperatures, highest elevations, and highest latitudes occurred on the C. lutosus and C. molossus sites, where hibernaculum insolation was higher than surrounding insolation. Temperatures were intermediate on the high-elevation C. atrox site, where hibernaculum insolation did not differ from random-point insolation, Temperatures were highest on the low-elevation C. atrox site, where hibernaculum insolation was unexpectedly lower than random-point insolation, Our observations suggest that rattlesnakes in cool climates utilize hibernacula with insolation values higher than those of their surroundings, Rattlesnakes in warm climates utilize hibernacula with insolation values lower than or similar to those of their surroundings.