Conditions at Backdoor in September
September: First Signs of Winter
September marks the gentle turn back toward winter. Average swell height is still modest at 1.7m (5.6ft), but the average period lengthens to 9.2s and the swell rose becomes more diverse. ENE remains the leader at 46.2%, with NE at 18.1% and E at 13.9%, yet NNW (5.5%) and N (4.2%) reappear - the first distant pulses of North Pacific storm swell. The trades still dominate the wind rose (ENE 44.0%, E 41.5%), but ideal offshore wind jumps to 23%, making the few clean windows more usable. A rogue north swell in September can produce genuine Backdoor barrels, though the size and frequency are nothing compared to winter. Air temperature averages 26.2°C (min 23.1°C, max 30.6°C), rain is 1.34 mm/day, and water temperature is at its yearly warmest, 26.7°C.
Average Spot conditions at Backdoor in September
Swell history for September
Wind history for September
Swell quality
Analyze the groundswell consistency at Backdoor 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 Backdoor for your next trip in September.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Backdoor 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 Backdoor.