The species' habitat includes montane areas of pine-oak, oak scrub, oak-juniper, and pine-fir woodland, foothill canyons in pinyon-juniper woodland, and relatively humid canyon bottoms with canopies of sycamore, alder, box elder, and maple, often along stream courses, in areas with rock outcrops or talus, or among downed logs (Lowe et al. 1986, Ernst 1992, Degenhardt et al. 1996, Ernst and Ernst 2003, Stebbins 2003, Campbell and Lamar 2004). At the southern end of the range, habitats include pine-covered plateaus with scattered open meadows, hillsides with scattered pines, oaks, madrones, and rocks, and brushy hilltops (Armstrong and Murphy 1979). This snake is basically terrestrial but may climb into low vegetation (Rossi and Feldner, 1993). It seeks cover in crevices, among or under rocks, wood, or other debris, in old stumps, or in similar sites.

The species' range extends from southeastern Arizona and extreme southwestern New Mexico south in the Sierra Madre Occidental through north-central and northeastern Sonora to western Chihuahua and (possibly disjunctly) to southern Durango and western Zacatecas, Mexico, at elevations of about 1,460 to 2,750 m (4,790 to 9,020 feet) (Campbell and Lamar 2004).

Subspecies obscurus occurs locally in the Animas Mountains (New Mexico), Peloncillo Mountains (Arizona and New Mexico), and Sierra de San Luis (Sonora and Chihuahua, Mexico) (Campbell et al. 1989, Holycross and Smith 1997, Campbell and Lamar 2004).

Subspecies willardi occurs in the Huachuca, Patagonia, Santa Rita, and Whetstone mountains of Arizona and southward into the Sierra de los Ojos, Sierra de Cananea, and Sierra Azul in north-central Sonora (Thirkhill and Starrett, 1992, Campbell and Lamar 2004).

Several occurrences of this species are in protected areas.