S. semiannulata is native to the Southwestern United States, in Arizona, Nevada, California, Colorado, Kansas, Missouri, New Mexico, Oklahoma, Oregon,[5] Texas, and Utah, as well as northern Mexico, in Chihuahua, Coahuila, Durango, Nuevo León, and Sonora.

The western ground snake can grow to a total length (including tail) of 8 to 19 inches (20.3 to 48.3 cm).

The diet of S. semiannulata consists primarily of invertebrates, such as spiders, scorpions, centipedes, crickets, and insect larvae.

The western ground snake is oviparous, breeding and laying eggs through the summer months.

Sonora semiannulata was once broken up into five separate subspecies, based on the vast differences in color and patterning that the species displays, but recent research has shown that the various colors and patterns of ground snake interbreed indiscriminately, making distinction between them impossible and thus not warranting subspecies status, though some sources still refer to them, using geography as a basis rather than morphology.