The hot spring snake is a small and medium-sized snake with a total length of 780-1000 mm, a short and small head, indistinguishable from the neck, 8 upper lip scales, 1 cheek scale, 2 preorbital scales, and 3 retroorbital scales. There are 2+3 temporal scales, 19-19-17 rows of dorsal scales, all ridges except the outermost row with smooth or weak edges, 205-218 ventral scales, and 96-120 pairs of inferior caudal scales.

In addition, the head and neck of the hot spring snake are clearly distinguished. The back of the tail is olive green, with three rows of dark brown patches, one of which is the largest, and the two outer edges of the dorsal scales are gray-green, forming several fine vertical lines of alternate depths.