I'm considering a move to California. Where can I go to sail year-round?
There are a number of locales on the California coast (as well as inland) where sailing happens on a year-round basis. Essentially anywhere from San Francisco south you'll find that this is the case. You'll probably also hear folks in Seattle and other ports in the Pacific Northwest brag that they sail year-round as well, but since you asked about California, we'll limit our answer to that state.
There's an abundance of activity in San Francisco Bay from racing to cruising to rallies and simple daysailing. As you move south, we would consider Santa Cruz and Monterey, Santa Barbara, Los Angeles, and San Diego. Of course there are a few smaller towns in between these, but each of the ones that we mentioned offers enormous fleets of boats and several of these places are close to interesting offshore destinations, like Catalina Island off Los Angeles, or the Channel Islands off Santa Barbara. In the Bay area, there are a number of good destinations inshore just up the American River Delta. As you head north from San Francisco, the natural harbors become fewer and farther in-between, which naturally translates into a lessening of sailing activity.
But from San Francisco south the air temperature rarely gets so cold that it prohibits sailing, so really you'll find plenty of sailing in these areas.
Good luck with the move.