Warm Water Upwelling in San Diego: When Summer Brings Cold Surprises
Every summer, San Diego surfers face the same paradox: the best swells of the year arrive just as water temps plummet. You’d expect July and August to deliver warm, glassy conditions. Instead, you’re peeling on a 4/3 at Blacks Beach while the air is 75 degrees. That disconnect is upwelling, and understanding it will transform how you read the ocean and plan your sessions.
What Is Upwelling and Why Does It Happen Here?
Upwelling is the process where deep, cold ocean water rises to the surface. It’s driven by consistent north-west winds that push surface water away from the coast, creating a vacuum that pulls nutrient-rich, cold water from 200+ feet below. San Diego experiences this phenomenon predictably each summer because of our geography and prevailing wind patterns.
The Scripps Institution of Oceanography, right here in La Jolla, has been tracking upwelling for decades. Their data shows that water temperatures along the San Diego coast can drop 10–15 degrees in just a few weeks when upwelling intensifies. In May, you might be comfortable in a shorty. By July, you’re buttoning up a full suit.
The Summer Swell Trade-Off
Here’s the deal: the same atmospheric conditions that bring upwelling also generate the consistent swells we crave. The north-west wind pattern that cools the water is the tail end of distant Southern Hemisphere storms. Those storms produce long-period groundswell that wraps around the Pacific and hits San Diego perfectly aligned for summer breaks.
Spots like Blacks Beach, Torrey Pines, and Sunset Cliffs light up from June through August with waist-to-head-high peaks. The swell is cleaner, more consistent, and longer-period than spring conditions. The trade-off? Water temps drop from the low 70s in May to the low 60s—sometimes even upper 50s—by midsummer.
If you’re charging Trestles or Cottons, you’re 20 minutes south and the water stays slightly warmer, but upwelling still affects the entire coast. The San Diego Bight—the curve of our coastline—actually traps upwelled water, concentrating the effect.
Seasonal Patterns and Timing
Upwelling typically peaks in July and August, though it can start as early as June and linger into September. The coldest water usually arrives 4–6 weeks after the most intense wind events. This is why early July might still feel relatively warm, but by late July, you’re in full winter-suit territory.
September is your sweet spot. Upwelling begins to relax, water temps recover toward the mid-60s, and swell remains solid from late-season Southern Hemisphere storms. It’s the perfect month for less thermal protection and maximum comfort.
Winter (December through March) brings the opposite pattern: warmer water (upper 60s), but choppier, more wind-affected conditions. Spring (April–May) offers the warmest water of the year (low-to-mid 70s) but smaller, less consistent swell.
How to Adapt Your Setup
Suit selection is non-negotiable. A quality 4/3 is your summer essential. Brands like O’Neill, Xcel, and Rip Curl all make San Diego-focused suits designed for upwelling conditions. Don’t cheap out—a cold suit kills your focus and shortens your session.
Gloves and booties extend your time in the water. Many locals add gloves in July when water temps dip below 62 degrees. Hood up when it hits the upper 50s.
Timing matters. Water temps are typically warmest in the late afternoon (4–6 p.m.), as surface water has had the full day to absorb sun. Early morning sessions at Blacks Beach in July are brutal; wait until mid-morning if you can.
Check the data. The Element app pulls real-time water temperature readings from NOAA buoys off San Diego. Knowing the exact temp before you paddle out lets you dial in your suit choice and plan session length accordingly.
The Silver Lining
Upwelling isn’t a curse—it’s a feature. That cold water brings nutrients that feed fish populations, creating better conditions for marine life. The swell quality during upwelling season is legitimately world-class. You’re not just dealing with cold water; you’re surfing some of the best conditions San Diego offers all year.
Locals who embrace upwelling season find empty, clean peaks while tourists assume the water is too cold. Blacks Beach, Windansea, and Pacific Beach are noticeably less crowded in July and August. That’s a gift.
Ready to Charge Summer Swells?
Use Element to track water temperature, swell period, and wind direction before every session. Knowing upwelling conditions are incoming helps you prepare your suit, plan your timing, and maximize comfort when summer brings its cold surprises.