The other thing about being anywhere near (i.e. within ~20 miles) of the coast in CA is the microclimates.
CD touched on this with his discussion of Napa. Napa Valley climate changes quite significantly between the north and south ends of the valley. Sonoma Valley isn't far away from Napa Valley (a small foothill range between them), but climate there is MUCH different. Hence why the same style of wine, made with the same style of grape, can taste very different based on where it's grown, all within a 15-20 mile range.
Take where I live, for example (red circle in Mission Viejo). You see the Crystal Cove State Park, as well as the empty areas between Aliso Viejo / Laguna Niguel and the coast. Those are all low-lying foothills. Nothing above I think maybe 1000-1200 ft elevation. But they block a good portion of the ocean cooling. So everything from Aliso Viejo and Laguna Niguel, straight up to me is a lot hotter due to those foothills.
Look to the north of me (Irvine and Tustin, just north) and you can see that there's a lot of roads/development between the coast (Newport Beach) and those cities will commonly be 5-8 degrees cooler than where I live in the summer. I can see it in my car's thermostat when driving home from work (off the 405 in Irvine). The minute I get to where the 405 and 5 meet, the temp shoots up.
Look to the south, and obviously Dana Point will be cooler. Again, if I'm going from my house south on the 5, there is a point where I can watch the car's thermostat drop 5-8 degrees in a mile. But curiously the area that *seems* more inland--the back route from my house to Rancho Mission Viejo, I see the same thing with temps once I hit a certain point cresting a hill because it's suddenly not blocked.
Then... Go over the much bigger mountains northeast of me (Saddleback range in the Cleveland Nat'l Forest) over to Lake Elsinore, and you're talking triple digits for most of the summer.
5 miles can mean BIG differences in climate here.
