Conditions at San Juan in December
December: A Glimpse of Winter Swell, Poorly Timed
December carries the largest ENE swell component of the year at 11%, with NE adding 2% and 3-5ft (1-1.5m) waves making up about 24% of the month. The average remains 2-3ft (0.8m) and period 6.2s, but for the first time in months there is real north-hemisphere groundswell in the mix. The problem is the wind: ideal condition drops to 19%, one of the lowest of the year. The trades are backed by a strong North Atlantic high, and E (35%), ENE (25%) and ESE (16%) keep the surface bumpy and cross-shore.
Still, when a strong front pumps swell into the NE Atlantic and the winds swing S/SW, San Juan can produce fun, peaky waves in the 3-5ft range. Air temps cool slightly to 25.5°C, water is a still-warm 27.4°C, and rain drops to 2.71mm/day. It is a month of high hopes and limited windows, but the seeds of the best winter surf are planted.
Average Spot conditions at San Juan in December
Swell history for December
Wind history for December
Swell quality
Analyze the groundswell consistency at San Juan 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 San Juan for your next trip in December.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at San Juan 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 San Juan.