Are you on a month-to-month lease? if you are, yes, they can give you a 30-Day notice to terminate any time of the month. Say they gave you the notice on 7/26, you have until 8/25 to vacate provided they don't accept your rent on 8/1. If they accept your rent on 8/1 for the full rent, they would waive the right to evict you since payment for the full month of rent in August would mean you've paid through August 31 (6 days beyond the termination date) which would invalidate the notice to terminate served on 7/26.
California Civil Code 1946 states ..."as to tenancies from month to month either of the parties may terminate the same by giving at least 30 days' written notice thereof at any time and the rent shall be due and payable to and including the date of termination." Therefore, either the landlord or tenant can give 30 days notice at any time and not just on a specific date of the month. Good luck!