Here is an idea to beat the heat and escape from the crowds: take a boat ride to one of the Channel Islands. Island Packers offers round-trip boat rides to Anacapa Island for $59.00. The 11-mile trip leaves from Channel Islands Harbor at 9:30am and takes about an hour. You will likely see dolphins, sea lions, and even whales on the ride to or from the island.
If you leave Los Angeles and go east on Interstate 10, you will come to a pass just east of Redlands. On the north side of the highway you will see Mount San Gorgonio (11,500 ft.) and south of the highway is Mount San Jacinto (10,804 ft.). Mt. San Jacinto is a California State Park. Here is a link to the web site.