Conditions at Sines in December
December: Deep-Water Power and Holiday Swells
December matches the midwinter intensity of January and February. Average swell height reaches 7.5ft (2.3m) with an average period of 12.7 seconds, so long-period, very powerful groundswell is the norm. Swell directions are spread among NW at 24.6 percent, WNW at 19.3 percent and W at 6.7 percent, with WSW and the south quadrant becoming more prominent than they were in summer. The persistent winter lows create a lot of motion in the water, but they also bring the lowest ideal-wind score of the year at 47 percent. That means you have to pick your windows carefully: after cold fronts pass, N/NNE/NE and NNW winds often blow offshore and groom the S/SW groundswell into clean, potentially epic surf.
Air temps average 12.1°C, rainfall is high at 2.55 mm per day, and water temperature is 15.8°C. Winter-grade rubber is essential, and the holiday swell potential is often the best gift of the year.
Average Spot conditions at Sines in December
Swell history for December
Wind history for December
Swell quality
Analyze the groundswell consistency at Sines 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 Sines for your next trip in December.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Sines 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 Sines.