Cal. Veh. Code § 38301.5
Every person convicted of violating a local ordinance which is adopted by a city with a population over 2,000,000 persons pursuant to Section 38301 and which prohibits entry into all or portions of an area designated by ordinance as a mountain fire district shall be punished as follows:
(c)
(1) For a third or subsequent offense committed within one year of two or more prior violations for which there were convictions punishable under this section, the offense is punishable as a misdemeanor by a fine not exceeding one thousand dollars ($1,000) or by imprisonment in the county jail not exceeding 90 days, or by both that fine and imprisonment. Additionally, the court may order impoundment of the vehicle used in the offense under the following conditions: