Civil Code §827.
In all leases of lands or tenements, or of any interest therein, from week to week, month to month, or other period less than a month, the landlord may, upon giving notice in writing to the tenant, in the manner prescribed by Section 1162 of the Code of Civil Procedure, change the terms of the lease to take effect, as to tenancies for less than one month, upon the expiration of a period at least as long as the term of the hiring itself, and, as to tenancies from month to month, to take effect at the expiration of not less than 30 days, but if such change takes effect within a rental term, the rent accruing from the first day of such term to the date of such change shall be computed at the rental rate which obtained immediately prior to such change; provided, however, that it shall be competent for the parties to provide by an agreement in writing that a notice changing the terms thereof may be given at any time not less than seven days before the expiration of a term, to be effective upon the expiration of such term.
The notice, when served upon the tenant, shall of itself operate and be effectual to create and establish, as a part of the lease, the terms, rents, and conditions specified in the notice, if the tenant shall continue to hold the premises after said notice takes effect.