Dawson Hartwig, 20, was last seen around 5 p.m. Friday when he left for a walk from a rented cabin near Lake Arrowhead. He did not bring a phone or other personal property with him.
Rescue crews and volunteers are searching the area near the lake as well as a dive team looking in the lake itself.
Hartwig is described as 6 feet 4 inches, 160 pounds, with blonde hair and brown eyes. He was last seen wearing a white shirt, khaki pants, snow boots and a beanie hat.
Anyone with information is asked to call the San Bernardino County Sheriff's department at (909)387-8313.