Summer
This is the only time you might be inspired to migrate south if you live somewhere north of Point Conception. Orange County flourishes during this period when southerly swells from New Zealand mean endless right walls at Trestles, boils at Brooks Street, barrel rolls at T Street, no parking at Salt Creek, wedgies at the Wedge and a Snake River-like current at Huntington Beach. And, since the water can be a balmy 70 degrees, you're enjoying all of this without the constriction of neoprene. Fall
Orange County is chock-full of beachbreaks, and beachbreaks like crossed-up swells. Add a hot, dry offshore wind called a Santa Ana, and you get what California should be year-round: an endless supply of A-frames while all the kiddies are back in school. Winter
What blesses Orange County in the summer curses it in the winter. Its southerly orientation tends to handcuff a number of breaks during the months between November and April, and it's not uncommon for the breaks in other counties, namely Ventura and San Diego, to be twice the size as spots like Salt Creek. But there are worse places to be during the winter, like Avalon on Catalina Island. Expect mild winters, nippy but manageable water temps (fullsuit, no booties). Spring
Once again, Orange County likes crossed-up swells. As soon as the southern hemisphere starts stirring in April, you have a good chance of finding some more of those sand-bottom A-frames. Go early, though, since Santa Anas are almost nonexistent. Keep the fullsuit handy, too: stiff afternoon onshores will keep the water temps at dead-of-winter lows.