Conditions at Rosa in September
September: Maximum Size, Variable Winds
September brings the largest average swell of the year at 5ft (1.5m), while the average period remains a solid 9.2s. The swell directions are heavily weighted toward the eastern quadrant: E (21%), ESE (19%), ENE (18%), SE (15%), SSE (12%) and S (9%). The height distribution is the strongest yet, with substantial amounts of 1.5-2m (5-6ft) energy from ENE, E and ESE, plus a notable share of 2-2.5m (6-8ft) waves. This is prime heavy, firing potential when conditions align.
The catch is wind. Ideal conditions fall to 31% as NNE (25%) and NE (16%) regain dominance, often with stronger speeds in the 20-30kph bracket. SSW (11%) and SW (11%) can still deliver offshore flow, but the windows can be shorter and more compressed between frontal systems. Water temperature starts to rise to 18.3°C, air averages 17.0°C, and precipitation increases to 4.67 mm/day. September offers the biggest waves of the year, but you have to time it well.
Average Spot conditions at Rosa in September
Swell history for September
Wind history for September
Swell quality
Analyze the groundswell consistency at Rosa 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 Rosa for your next trip in September.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Rosa 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 Rosa.