If you tried to dive the Southern California coast in the last week of July, you already know: a run of big south swells stirred the bottom and blew the inshore visibility to pieces right when the summer bloom had finally started to settle. That's not bad luck — it's the season. Late summer is Eastern Pacific hurricane season, and distant tropical systems off Baja and mainland Mexico fire long-period south swells straight at our coast for weeks at a time. Here's the fix.

August is the warmest month of the year in California waters — and, in a normal year, the tail end of the peak plankton bloom. But 2026 has been anything but normal. After an early June bloom and a persistent marine heatwave that defined July, August arrives with the surface as warm as it will get all year and the coastal murk finally starting to ease.

If June 2026 was the month the bloom ambushed California six weeks early, July was the month divers learned to live with it. The plankton didn't vanish — but a persistent marine heatwave, a warm surface lens, and a reliable afternoon clearing pattern gave patient divers real windows. This is what actually happened in the water in July, region by region, grounded in dozens of in-water reports and the offshore intel that shaped the month.

July is historically California's peak plankton bloom month. Warm surface water, abundant sunlight, and nutrient-rich upwelled water create optimal conditions for explosive algae growth. In most years, July's bloom is less severe than it appears because higher swell mixes the water column and breaks apart surface accumulations.

June 2026 will be remembered as the month the bloom came six weeks ahead of schedule. Across California's dive zones—from Monterey to San Diego—the combination of marine heatwave warmth at the surface and persistent cold-water upwelling at depth created a perfect storm for plankton productivity. The result: an early-June red tide event that hammered visibility from the Bay Area through Orange County, with only offshore pinnacles and depth-access sites offering reprieve.

Southern California's forecast for May 2026.