Month to month lease termination in California question

[Kevin Ryan]

I own a SFR here in California. My tenant signed a year lease just about a year ago. He told me 90 days or so ago that he'd like to go month to month when his lease expires which I agreed to. His lease expires this Friday, 5/31. He dropped off his check off today with a letter stating he will be leaving 7/20 so he gave me a check for the month of June and 20 days of July @ $100/day. I was under the impression month to month means you're renting the home for the entire month. Am I within my rights to ask for the entire months rent ($3000) or is he within his rights to prorate the check and leave on the 20th?

Any advise specific to California would be appreciated!! Thanks!