Katahama - surf spot statistics

Katahama, Japan, offers a mix of wind swells and ground swells throughout the year, with varying wind conditions that influence surf quality. The best months for surfing here are typically from August to October due to a combination of higher ground swell presence, more favorable wind conditions, and consistently decent swell size. During this period, ground swells make up 28-32% of the swell activity, which is significantly better than the rest of the year, and wind conditions improve slightly compared to earlier months. September stands out with the largest mean swell size (1.5m) and a decent ground swell contribution (30%), though wind conditions are less favorable (only 26% good wind days). August and October also provide solid surf conditions with ground swells around 28-32%, mean swell sizes of 1.4m, and moderate wind conditions (34-37% good wind days). The winter months (January-February, December) have a reasonable ground swell presence (around 28-29%) but suffer from poor wind conditions (70-71% bad wind days), making sessions less consistent. Spring and early summer (March-July) are dominated by wind swells (80-94%), which often create choppier, less clean waves. July shows a slight improvement in wind conditions (39% good days) but remains predominantly wind swell-driven. If you prioritize cleaner, more powerful waves, late summer to early autumn (August-October) is the prime window, though wind consistency isn't perfect. Outside of this period, surfers will face either weaker ground swells or onshore winds that reduce wave quality.

Katahama in January offers surfable conditions with a moderately consistent swell, averaging 1.1m at 8.4 seconds, providing enough energy for decent rides. The most dominant swell directions are from the west (W, WSW) with a significant portion of waves in the 1-2m range, occasionally reaching overhead heights (over 2.5m). ENE, E, and ESE swells also contribute, though smaller in size. Wind conditions are variable, with only 29% of the time being ideal (typically light offshore or sideshore winds from the NE to E quadrants). However, strong onshore winds from the W and WNW are common (up to 30-40+ kph), which can degrade wave quality. Surfers should watch for windows of cleaner conditions when winds shift lighter from favorable directions, particularly early mornings. Overall, January delivers rideable waves, but wind interference can be a limiting factor—patience and timing are key for scoring the best sessions.