Shonan - surf spot statistics

Shonan, Japan, offers varying surf conditions throughout the year, with the best windows for consistent waves and favorable winds typically occurring in late summer and autumn. The swell data shows that ground swells, which provide cleaner and more powerful waves, are most frequent from August to October, peaking in August at 16%. Wind swells dominate the rest of the year, particularly from March to May and again in October, with percentages above 60%. However, wind conditions are generally poor across all months, with good wind days rarely exceeding 15% (best in October and November). The mean swell size remains modest, averaging 0.6m to 0.8m, with slightly larger waves in March, September, and October. For surfers seeking the most reliable conditions, September and October stand out as the prime months. These months combine a higher percentage of ground swells (15% and 14%, respectively) with slightly improved wind chances (13% and 15% good wind days) and a mean swell size of 0.8m. Late summer (August) also sees a spike in ground swells, though wind quality remains poor. Winter months (December-February) and early spring (March-May) offer more wind swells but suffer from consistently bad onshore winds. Summer (June-July) tends to be the least favorable, with smaller swells and persistent poor winds. Overall, autumn provides the best balance of swell energy and marginally better wind opportunities for surfers willing to wait for clean sessions.

April at Shonan offers mixed conditions for surfers. The average swell height is **0.8m** with a **7.6s period**, typically producing small to occasionally waist-high waves. The swell distribution shows the most likely directions are **ESE (11.7% for 0.5-1m waves)** and **SE (7.2% for 0.5-1m)**, but larger swells (1.5m+) are rare. Cross-shore or light onshore winds (SSE-SSW) are the most frequent, though they can sometimes degrade wave quality. **Only 12% of the time** will winds be ideal (light offshore or glassy). Expect **mostly clean conditions early mornings** before winds pick up. Most swells are under 1.5m, with only **3-5% reaching 2m+** (from SSW/S directions). Overall, April leans toward smaller, weaker waves with occasional fun-sized days for logs or high-volume boards when winds align. Windy or choppy sessions are common, so timing around early sessions or rare offshore days is key.