Katahama - surf spot statistics

Best Surf Season (March - May)

Spring at Katahama brings the most consistent combination of favorable swell and offshore winds. As the Siberian high weakens and the North Pacific storm track becomes more active, pulses of mid-period swell from the ESE and SE quadrants become dominant. Ideal winds from W and WNW blow 28-31% of the time, sculpting clean, rippable waves in the 1-2m range with periods averaging 7-8s. This is the window to score punchy, fun surf along the sandbars.

Fair Surf Season (June - August & November - February)

Summer sees a shift to more southerly and SSW swell that can wrap into the beach but often lacks the angle and power of true ESE groundswell. Offshore winds remain relatively common (28-33% of the time), but the predominant swell direction is less optimal. In winter, powerful offshore winds from W and NW dominate (ideal wind 24-28%), but the swell is mostly from W and WNW – a direction that doesn't favor this east-facing stretch. Still, when a SSE or E component sneaks in, the combination can be epic. Fair season surf requires patience and flexibility.

Low Surf Season (September & October)

Early autumn is a frustrating period for Katahama. The North Pacific churns out some of the most powerful, long-period swells of the year, with E and ESE groundswell dominating the averages (heights 1.3-1.4m, periods 8.8-9.2s). However, the wind patterns are brutally unfavorable – a prevailing NE and ENE monsoon blows strong and onshore over 50% of the time, trashing wave quality. Only 23% of the time do we see offshore winds. When the stars align, the waves can be pumping, but the low consistency makes it a gamble.

September: Great Swell, Wrong Wind

September is a study in frustration. The average swell height climbs to 1.4m with a period of 9.2s – the best of the year. ESE (20%), SE (17%), E (13%), and SSE (14%) combine for 64% of all wave energy, offering incredible potential. But ideal wind plummets to just 23%, with strong onshore ENE (23%) and NE (11%) winds ruining the quality for days at a time. Surfable conditions are rare – you need a frontal passage or a typhoon to shift the wind west. Those windows are pure gold.