Conditions at Kugenuma in December
December: Winter Swell Legacy and Cold-Weather Cleanups
December closes the year exactly where it started: with strong SW swell production and firm offshore winds. The SW direction accounts for 27.6% of all swell, SSW adds 12.1%, S contributes another 7.1%, and SSE adds 6.4%. These numbers give Kugenuma one of the highest optimal-direction swell percentages of the year, making winter the true high season. The average height remains 0.7m and the average period is 8.1s, so waves are not oversized but are usually rideable and punchy. Wind again comes from the north: NNE (26.9%), NE (12.8%) and N (8.9%) dominate, with SW and WSW as secondary onshore components. The ideal-wind frequency is 17%, but the number of clean, offshore days feels higher because the north wind is so persistent. Precipitation is the lowest of the year at 1.87 mm/day, meaning crisp, cold, sunny days and strong offshore flow are common. Air temperatures average 4.9°C and water is 18.1°C. For a surfer, December is all about dawn patrols, thicker wetsuits, and trading summer warmth for the cleanest, most reliable surface conditions of the year.
Average Spot conditions at Kugenuma in December
Swell history for December
Wind history for December
Swell quality
Analyze the groundswell consistency at Kugenuma during December. 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 Kugenuma for your next trip in December.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Kugenuma for December. 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 Kugenuma.