Legal Question in Landlord & Tenant Law in California

It depends whose calendar you're looking at. In my mind, a "natural" month," which seems to parallel the Jewish (and maybe Chinese) calendars, is the precise time between the new moon and the end of the last crescent moon. A Gregorian calendar month seems to be roughly -- but not fully -- equivalent. Have you been watching lunar cycles to determine when you should give notice? The language used is vague and should be attributed to the drafter; therefore it probably is unenforceable, and one calendar month's notice should be all that is required.