An extreme heat wave off California’s coast seemed like an anomaly 10 years ago. But as the ocean warms, the catastrophe may be a glimpse of the future. Rodeo Beach, Calif., one of the beaches ...

At about 3:15 p.m. on Dec. 23, as a powerful winter swell raged on the California coast and left the Santa Cruz Wharf snapped and floating in the ocean, Alessandro “Alo” Slebir pointed his surfboard ...