I haven't been down that way in a couple years, but I saw a couple roadkilled along a popular lakeshore. A local kid on a bike noticed me checking out a squashed snake and before he was close enough to see it he guessed it. "Kingsnake right?" I told him yeah, he looked as he passed and nodded in agreement. He was so non chalant about it, like he sees them every day.
I haven't explored much further South than that, but if you stay in that same climate band your chances should be good. Elevation of around 3000 feet, in the ponderosa pine belt.
My dad has a picture of one in Yosemite. He walked around a corner in a trail and his ditzy girlfriend was holding it by the tail, saying "I think it's a coral snake."