Choshi seasonal overview
Best Surf Season (October - March)
The winter months deliver the most consistent offshore wind conditions thanks to the strengthening Siberian High. Average wind ideal rates climb to 40-47% from November through January, with winter storms spinning up across the North Pacific and sending long-period groundswell. While the dominant swell direction is from the northeast, the south-facing beaches of Choshi still pick up a mix of ENE and E swell that can produce punchy, rideable waves. The average wave period hovers around 9.5-9.9s, offering solid power. Still, when a storm tracks favorably, we can see SSW or SW swell with offshore N winds - that is when the stars align for Choshi's best waves.
Fair Surf Season (April, September)
April sees a shift in the dominant swell window to more easterly and southeasterly directions, increasing the potential for good wave angles. September is a transition month where tropical systems in the Western Pacific can fire up SSE and S swells, often with light offshore winds early in the season. These months average 1.6-1.7m wave heights with periods around 9.2-9.4s, providing fun-sized conditions for the dedicated surfer, though the wind ideal percentage drops to 26-35%.
Low Surf Season (May - August)
Summer in Choshi is dominated by the East China Sea monsoon pattern, bringing persistent S to SW winds that are mostly onshore. While the swell direction turns favorable toward SE and S, the wind quality deteriorates significantly, with ideal wind rates dropping to 25-31%. Wave heights average 1.2-1.4m and periods shorten to 8.6-8.9s, resulting in small, choppy conditions. Occasional typhoon swells can break the monotony, but they are usually accompanied by strong onshore winds and dangerous surf.
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Conditions at Choshi in September
September: Autumn Awakening
September is a turning point: average height reaches 1.6m, period 9.4s. Swell from E (26.1%) and ENE (22.9%) leads, with some SE (8.4%) still in the mix. Offshore wind frequency climbs to 35%, with NE (21.1%) and NNE (14.2%) breezes becoming more common. Waves in the 1-1.5m and 1.5-2m ranges are abundant. This month often delivers the best combination of improving wind and leftover summer swell angles. Keep an eye on tropical remnants for SSW swell with offshore north winds.
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.
