Drive California’s northern and central coast and you’ll mostly see surfers in wetsuits, beachcombers and sand sculptors. But along Southern California’s sunny and warm coast, you’ll see more sunbathers and people splashing in the waves. Summer water temperatures average from about 50 F in Northern California to 70 F in southern California, making the southerly beaches the most swimmable. Water quality and waves also play a role.
Summer’s surface near-shore waters in Southern California range from the mid- to high-60s, with the exception being Newport Beach, which reaches 70 F in August. If you’re going for a quick swim, you’ll likely be fine with just a swimsuit or swimsuit and rash guard. If you’re swimming for an a half hour or more, you may need a shorty or full wetsuit. In summer, surfers where shorties and full wetsuits. According to the U.S. Search and Rescue Task Force