Many of CA state beaches will fill up in minutes for the main summer month when the reservation window opens. Some campgrounds will fill up everything right away while there can be various spots of reservations available at other campgrounds.
I have been able to pick up reservations at ReserveAmerica when someone cancels. I have done more than my share of cancelling plans when things didn't work out. It's a long shot but worth the effort. At RA it is possible to request a notification notice if availablity comes up but the notification notice does not hold the reservation. Friday & Saturdays usually don't come up often and usually get taken real fast.
A few weeks ago I got reservations for a couple of day for the 4th of July holiday at Crystal Cove More state beach. Then two weeks I got a couple of days at El Captian for mid June that works with my schedule. Last summer my neighbor was searchng for a week at the beach and couldn't find anything available. A few days later I found two spots that had 6 days available.
Try playing around with various dates or number of days to see if there any choices that could work for you.
At the state beaches you have until 12 noon or 2 pm the following day to check in or lose your reservations. Once I had to call the state park to make arrangements not to cancel my reservations as I would be arriving early morning on the third day due to a family matter.
2011 Salem Cruise Lite 20RBXL by Forest River / 2011 Toyota Tundra
Great Choice for "Living within my means" and Camping for one...