Conditions at Choshi in September
September: Autumn Awakens with Tropical Groundswell
September is a standout shoulder month at Choshi. The average swell height has recovered to 5ft (1.6m), periods are a solid 9.4s, and the ideal wind frequency jumps to 35%. The wave direction data is dominated by E and ENE swells, together nearly 50% of the observations, but the SE/S/typhoon component remains in play. This is still the Western Pacific tropical cyclone season, and the warm water temperatures at 23.6°C fuel late-season storms that can deliver long-period, east-southeast groundswell to Japan. Winds are turning more favourable, with NE as the leading offshore direction at 21% and NNE/ENE also well represented, although SSW/S can still spoil a weekend. Precipitation remains high at 6.84 mm/day as frontal systems begin to increase. The surf is often still a little sectiony from summer swell, but the autumn transition is underway. When the first cold front sweeps through with N/NNW winds, the south-facing banks clean up and the surf starts to feel serious again.
Average Spot conditions at Choshi in September
Swell history for September
Wind history for September
Swell quality
Analyze the groundswell consistency at Choshi 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 Choshi for your next trip in September.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Choshi 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 Choshi.