Conditions at Haleiwa in September
September: The First Stirring of Autumn
September is the bridge between summer flatness and winter power. Average swell height remains small at 5.5ft (1.7m), but the period stretches back to 9.2s, a sign that longer-period energy is starting to return. Trade swell still dominates - ENE is 46.2%, NE is 18.1%, and E is 13.9% - yet there is a noticeable uptick in the good directions: NNW jumps to 5.5% and N to 4.2%. It is not enough to make Haleiwa fire consistently, but the ocean is beginning to breathe.
The wind climate turns in your favor too. Ideal offshore/sideshore flow is present 53% of the time, the highest reading of the year, and the trades are less aggressive than in July and August. Water temperature is at its yearly peak of 27.0°C, air sits at 26.2°C, and rain remains light. September is a month for small-wave practice and optimism - the first serious pulses usually appear as we move deeper into fall.
Average Spot conditions at Haleiwa in September
Swell history for September
Wind history for September
Swell quality
Analyze the groundswell consistency at Haleiwa 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 Haleiwa for your next trip in September.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Haleiwa 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 Haleiwa.