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Conditions at Upper Trestles in September
September: The Autumn Flip Starts to Stir
September marks the first real shift in surface conditions. The average swell is 3ft (1.0m) with a 13.6s period, and the direction remains heavily in the Trestles sweet spot: SW 41.8%, WSW 34.0%, SSW 16.0%, W 7.6%. The 2-3ft (0.5-1m) class is most common, but there are enough 3-5ft (1-1.5m) pulses to keep Lowers interesting. The big change is wind: ideal offshore flow jumps to 22% as N/NE winds begin to reappear, while WSW and W winds start to weaken compared to summer. Water temp holds at a warm 18.2°C, air cools slightly to 22.4°C, and precipitation stays low at 0.17 mm/day. This is also prime eastern Pacific hurricane season; a well-timed tropical system can deliver a rare, clean S-SSW swell to Upper Trestles with almost no wind. September is the true crossover month.
Average Spot conditions at Upper Trestles in September
Swell history for September
Wind history for September
Swell quality
Analyze the groundswell consistency at Upper Trestles during September. Based on historical data, there is a % probability of groundswell occurring this month. The chart below provides a detailed breakdown of the average wave height distribution, offering deep insights into the swell quality and surf potential you can expect at Upper Trestles for your next trip in September.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Upper Trestles for September. Our analysis shows that favorable offshore or side-shore winds coincide with surfable swell approximately % of the time. The accompanying graph illustrates the average size distribution of waves during these optimal wind windows at Upper Trestles.