Upper Trestles - surf spot statistics

Upper Trestles is a high-quality surf spot that benefits from consistent ground swell year-round, though the best conditions are typically found between April and October. During these months, ground swell dominates (90%+ of the time), with minimal wind swell interference, making for clean, well-organized waves. The mean swell size hovers around 0.8-0.9m, providing ideal conditions for performance surfing. However, wind conditions are often less favorable, with bad onshore winds occurring 60-75% of the time, peaking in May and June. The late summer and early fall months (September-October) offer slightly better wind conditions, with good winds around 38-39% of the time, improving wave quality despite the swell size tapering slightly. Winter months (November-March) see more variability, with increased wind swell and no-swell days, while ground swell remains strong but less reliable. December and January have the highest chance of no swell (25-31%) and the smallest average wave heights (0.7m). For the best balance of swell consistency and manageable wind conditions, September and October stand out, though dedicated surfers can find good waves from late spring through early fall if willing to work around the frequent onshore winds.

August at Upper Trestles tends to offer relatively small but clean conditions, with an average swell height of 0.8m and a favorable period of 14.9s, indicating long-period energy that helps maintain quality even at smaller sizes. The primary swell direction is predominantly from the SSW (62.97% of waves in the 0.5-1m range), with SW and S also contributing, ensuring consistent but typically waist-high surf. Larger waves (1-1.5m) are less frequent, peaking at 6.14% from the SSW and 1.31% from SW. Wind conditions are the biggest variable, with ideal offshore or light cross-shore winds (under 20kph) occurring 33% of the time. The most problematic winds come from the W/WSW, which account for a notable percentage of higher wind speeds (10-30kph), potentially creating onshore chop. However, mornings often see lighter winds, providing cleaner sessions. Overall, August is consistent but rarely huge, best suited for high-performance surfing or longboarders when the wind cooperates. Expect small, playful waves with occasional waist-high+ sets and a mix of clean and choppy conditions depending on the wind.