Conditions at Yerbabuena in September
September: First Stirrings of Autumn
September is a transition month, and you can feel the North Atlantic begin to wake from its summer sleep. The average swell is still modest at 3.0ft (0.9m), but the period extends to 8.5s, a step closer to organized groundswell. WNW remains dominant at 45.5%, with E at 16.0% and W at 14.8%. More importantly, the incidence of S/SW swell starts creeping back from the summer zero; it is still small, but those first swells from the old winter storm track hint at what is coming.
Surf quality is still limited by the tail end of the summer trade winds. Ideal offshore wind is at 23%, much like August, and E/ESE flow remains strong at 39.4% combined. Still, with water temperature at 20.0°C and air at 21.9°C, it is a pleasant time to be in the water, especially if you find an early-season NW groundswell with a light N/NNW wind. Rainfall begins to pick up at 0.79mm/day, marking the seasonal shift.
Average Spot conditions at Yerbabuena in September
Swell history for September
Wind history for September
Swell quality
Analyze the groundswell consistency at Yerbabuena 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 Yerbabuena for your next trip in September.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Yerbabuena 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 Yerbabuena.