Before setting off on a camping trip anywhere in California, I always check weather and road conditions, which are particularly important in autumn when an early "winter" storm can close roads in the mountains and make campgrounds too soggy for a tent. This summer and autumn in our bone-dry state, I'm thinking that fire conditions (http://www.fire.ca.gov/index_incidents.php) will be even more important than roads or weather.
So far this spring and early summer we've had significant fires in the north and south of the bay area, and in forests near Big Sur, Redding, and Yosemite (just to name a few). Some of my favorite car camping destinations this time of year include remote sections of Plumas National Forest, Lassen National Forest, and the forests around Yosemite National Park. I feel uneasy planning a trip in any forest this summer or autumn, since it seems that no place is safe from fires.
So where to go? Maybe the safest bet would be someplace immediately on the coast, with easy access to a large paved road and few trees. That rules one of my favorites, Gold Bluffs Beach up in Prairie Creek Redwoods (too far from the road, too many trees).
Salt Point State Park
Van Damme State Park
MacKerricher State Park
Manchester State Park
Patrick's Point State Park
Any other ideas? How about a yurt in Oregon?