The name trivirgata means three-stripes. It has a heavy- bodied build, a short, blunt tail and small head. Its eyes have elliptical pupils like those of a cat.
Coloration includes shades of gray, tan, or reddish brown.
Individuals from the coast and foothills may be, on occasion, nearly a uniform gray or brown color, with less defined stripes. Individuals from the desert tend to exhibit a more distinct pattern of stripes. All appear to intergrade widely and their different color patterns appear to correspond to the ecogeography of the areas they are found. The Rosy Boa ranges from southern California and western Arizona in the United States, southward to Baja California and western Sonora in Mexico. This species inhabits rocky areas in coastal sage scrub, chaparral, and desert environments.