California Code, Government Code - GOV § 65859

(a) A city may, pursuant to this chapter, prezone unincorporated territory to determine the zoning that will apply to that territory upon annexation to the city.

The zoning shall become effective at the same time that the annexation becomes effective.

(b) Pursuant to Section 56375, those cities subject to that provision shall complete prezoning proceedings as required by law.

(c) If a city has not prezoned territory which is annexed, it may adopt an interim ordinance pursuant toSection 65858.