Conditions at Oniguchi in December
December: Maximum Northwest Punch
December is the biggest month of the year on average, with swell heights reaching 1.3m (4.3ft) and an average period of 7.6s. Ideal offshore wind remains high at 60% of the time. The swell rose is strongly northwest: NW is 32.8%, NNW is 13.9%, WNW is 12.1%, while ENE and E each contribute around 7%. The optimal SSW-SW-W sector is small, but the higher WNW/W energies can produce the best quality waves of the season. Wind data shows NNW at 41.0% and NW at 15.2%, with NNE/N adding another 15.7%-a very favorable setup for a southwest-facing beach. Air temperature averages 14.5°C, water temperature is 20.9°C, and precipitation is lower at 3.41 mm/day. December is all about consistency: even if the direction is not perfect, the combination of size, period and offshore flow means Oniguchi is rarely flat. The standout days come when the swell angle shifts into the WNW/W window and the wind settles into the NO/ONO quadrant.
Average Spot conditions at Oniguchi in December
Swell history for December
Wind history for December
Swell quality
Analyze the groundswell consistency at Oniguchi 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 Oniguchi for your next trip in December.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Oniguchi 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 Oniguchi.