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.

April at Upper Trestles tends to offer fairly consistent but smaller surf, with an average swell height of 0.8m and a solid period of 14.9s, indicating clean, well-spaced waves. The majority of swell comes from the SSW (49.5% of waves in the 0.5-1m range) and SW directions, with occasional contributions from WSW and S, ensuring rideable conditions most of the month. Larger swells (1.5m+) are rare but possible, mostly from SW, WSW, and W directions. Wind conditions are less ideal, with only 30% of days offering favorable offshore or light winds for surfing. The predominant winds are from the W and WSW, often blowing in the 10-20kph range, which can create chop or cross-shore conditions. However, lighter winds (0-10kph) are frequent from multiple directions, providing cleaner sessions, especially early in the day. Overall, expect smaller but clean waves with occasional mid-sized pulses, though wind quality is inconsistent—timing sessions around lighter or offshore winds will be key.