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Conditions at Cottosloe in September
September: Spring Ahead - Swell Remains, Winds Turn South
September is a transition month: the swell is still oversized, averaging 2.6m (8.5ft) with a 13.0s period, but the direction starts to rotate back toward the SW (35.9%) and SSW (4.1%), with WSW still decent at 14.3% and W at 2.0%. The wind pattern is the real giveaway that spring is arriving - ideal offshore flow drops to 32%, while S (9.0%), SSW (9.9%), and WSW (9.5%) winds become more common, bringing side-shore and onshore conditions. That makes wave quality inconsistent, though the raw power is undeniable. Water temp is at its minimum of 18.0°C, air warms slightly to 15.8°C, and rainfall drops to 2.56 mm/day. Look for the days with an early morning ESE breeze - they can still deliver firing, hollow waves.
Average Spot conditions at Cottosloe in September
Swell history for September
Wind history for September
Swell quality
Analyze the groundswell consistency at Cottosloe 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 Cottosloe for your next trip in September.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Cottosloe 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 Cottosloe.