Conditions at Shonan in January
January: Offshore Winter Grit and the First Real Southern Swell
The surf year at Shonan is in full swing by January. Strong Siberian High pressure drives cold continental air across Japan, setting up a dominant NNE wind flow that is offshore for the south-facing coast. The ideal-wind reading is 17%, with NNE (29.3%) and N/NW/NNW contributions providing clean windows between bouts of NE cross-shore and WSW/SW onshore flow. Meanwhile the Pacific storm track sends mixed swell into Sagami Bay: the average wave height sits at around 2.3ft (0.7m) and the average period at 7.8s, putting most waves in the punchy, rideable 6-9s category. Although SW is the single most common swell direction (29.2%), the waves that really light up Shonan come from SSW and S, which show up with 2-3ft (0.5-1m) and occasional 3-5ft (1-1.5m) sets. With air temperatures around 2.3C and water temperatures at 16.2C, it is cold, but the reward is some of the cleanest waist-to-shoulder-high surf of the year.
Average Spot conditions at Shonan in January
Swell history for January
Wind history for January
Swell quality
Analyze the groundswell consistency at Shonan 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 Shonan for your next trip in January.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Shonan 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 Shonan.