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.

June at Upper Trestles offers relatively small but clean conditions with a dominant swell from the SSW and SW directions. The average swell height is 0.8m with a long period of 15.2s, indicating well-spaced, consistent waves. Most waves (59-65%) arrive in the 0.5-1.5m range, ideal for intermediate to advanced surfers looking for fast, rippable walls. Larger waves above 1.5m are rare, occurring less than 0.2% of the time. Winds are a mixed bag—light to moderate (0-20kph) and variable in direction, but WSW and SW winds (15-25% frequency) can create onshore chop. Only 25% of days provide ideal offshore winds (typically NW to NE), which are crucial for glassy conditions. Early mornings tend to be cleanest before sea breezes pick up. Expect small but quality waves, best suited for performance surfing when winds cooperate.