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.

January at Upper Trestles tends to offer a mix of surfable conditions with a dominant swell direction from the southwest and west-southwest, which aligns well with the break. The average swell height is modest at 0.7m, but with a solid period of 14.1s, indicating clean, well-spaced waves that often hold their shape nicely. The most consistent wave heights fall between 0.5-2m, with WSW and SW swells delivering the majority of rideable waves—particularly in the 0.5-1.5m range. Larger sets in the 1.5-2.5m range do occur but are less frequent. Wind conditions are favorable 35% of the time, typically light offshore or side-offshore (E-ENE), which helps maintain clean faces, though onshore winds (W-WSW) can occasionally chop things up, especially when speeds exceed 20kph. Overall, expect smaller but quality sessions early in the day before winds pick up, with the best days coinciding with those mid-period SW or WSW swells and lighter easterly breezes. It's not a big-wave month, but the consistency and shape make it a solid option for performance surfing.