Upper Trestles - surf spot statistics

Best Surf Season (December - February)

The heart of winter delivers the most consistent combination of quality swell and favorable winds at Upper Trestles. With offshore flow from the north through east-northeast prevailing over 57% of the time in December and January, and over 46% in February, the lineup is often glassy or lightly textured. Long-period groundswells (averaging 12.4-12.6s) from the west-southwest and southwest fill in, wrapping well into the cobblestone point. While the dominant swell direction is actually west, the southwest and west-southwest components provide the most direct, punchy lines. Expect waves in the 1-1.5m range frequently, with occasional pumping sets above 1.5m.

Fair Surf Season (October - November & March)

The shoulders of winter offer a mixed bag. October and November still see decent offshore wind percentages (35% and 50%, respectively) as the North Pacific begins to stir, but the swell direction shifts more toward west-southwest and west, often requiring a more selective approach. March brings the transition into spring with ideal wind dropping to 31% and more onshore flow from the southwest. Swell heights remain around 1-1.5m on average, and periods hold in the 12-13s range. Good sessions are still possible when a cold front clears the coast and sets up clean, offshore conditions.

Low Surf Season (April - September)

From April through September, Upper Trestles battles persistent onshore winds from the south, southwest, and west-southwest that degrade wave quality. Ideal offshore wind plummets to just 9-22% during these months, and the wind tends to favor light onshore breezes that create bumpy, choppy conditions even when swell is present. The swell itself shifts to a mix of southern hemi groundswells and local windswells, with heights averaging around 1m and periods around 13.5s – powerful but often poorly shaped due to the wind. May, June, and July are the worst, with only 9-10% clean windows. A few early morning or late evening windows can produce fun, rippable waves, but consistent quality is rare. This is the time to chase early dawn patrols or look for protected nooks.

July: Peak Summer, Marginal Quality

July offers only 10% ideal wind, with the dominant onshore flow from WSW (28.8%), W (18.5%), and SW (16.9%). Swell averages 1.0m at 13.7s, with a strong input from the southern hemisphere. Swell direction is the best of the summer: SW 47.3%, WSW 29.8%, and SSW 17.6% – nearly all in the optimal window. But the persistent onshore breeze creates lumpy, crumbly conditions. Heights are mostly 0.5-1.5m, with very few larger sets. The small windows of clean surf usually come at dawn or dusk, or when thunderstorms or eddy effects turn the wind offshore. For consistent quality, this is not the time.