Conditions at Ondarreta in December
December: Peak Winter Reliability
December delivers the highest ideal-wind percentage of the year at 49%, making it a top-tier month for clean winter surf at Ondarreta. The ocean is still grinding with an average swell height of 2.0m (6.5ft) and a 12.4s average period. Swell direction remains dominated by NW (28.1%) and WNW (24.4%), with NNW at 8.5% and W at 4.4%. Bigger waves are present throughout the distribution: 7.9% in the 1-1.5m (3-5ft) class, 9.1% at 1.5-2m (5-6.5ft), 6.7% at 2-2.5m (6.5-8ft), and an occasional XXL pulse over 2.5m (8ft+).
It is also one of the windiest months in terms of favourable direction. S winds blow 23.8% of the time, SSW 10.4%, SW 4.5%, and the wider southern quadrant adds more variety. With air temps averaging 9.9°C and water dropping to 14.2°C, it is proper winter surfing. Expect cold fronts, rain at 3.69 mm/day, and occasional windows of bluebird skies and offshore south wind right after a storm-exactly the conditions that make December one of the most reliable months of the year at this spot.
Average Spot conditions at Ondarreta in December
Swell history for December
Wind history for December
Swell quality
Analyze the groundswell consistency at Ondarreta 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 Ondarreta for your next trip in December.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Ondarreta 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 Ondarreta.