Conditions at Katahama in January
January: Winter Monsoon Grip
January is the heart of the winter monsoon, with the wind rose dominated by a powerful west-northwest flow. Winds blow from the W (36.5%) and WNW (29.8%) - both offshore for Katahama's ESE-facing aspect - meaning the bay is often glassy and groomed. However, the swell direction tells a different story: the same storms that drive those offshore winds also produce a wave train that wraps in from the west, with WNW (34.1%) and W (22.9%) swells dominating. These are not the E, ESE, SE, and SSE directions that light up this beach. The result is a month of clean but relatively weak surf, as the short-period (6.6s) WNW windswell struggles to break properly on the open beach. The average swell height of 1.3m (about 4ft) is rideable, but you'll be scanning the forecast for those rarer E and ESE pulses - totaling around 15.8% of the swell distribution - to find any real shape. Air temperatures average 9.2°C, water temps drop to 15.4°C, and precipitation is relatively low at 2.42 mm/day, so it's often crisp and sunny between storms. A 4/3 wetsuit is mandatory.
Average Spot conditions at Katahama in January
Swell history for January
Wind history for January
Swell quality
Analyze the groundswell consistency at Katahama during January. 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 Katahama for your next trip in January.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Katahama for January. 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 Katahama.