Playa Rio Mar • Statistics for December

December: Strong NNW Offshore Winds and Mixed Swell Angles

December signals the return of the winter trade-wind regime. The wind blows offshore and hard -- NNW accounts for 72.8 percent of all wind, with N and NW adding more -- and the ideal-surf rating reaches 75 percent, the highest of the year. The swell mix, however, is split. The SSW quadrant still produces 33.1 percent of the swell, but the non-optimal N, NNE, and NNW quadrants combine for around 38 percent, so direction is much less clean than in summer. The average period drops to 8.9 seconds, favoring punchy, short-period waves at 2 to 3 feet (0.6 to 1m). There can still be fun 3 to 5 foot (1 to 1.5m) waves from the N/NNW windswell, but they are not the ideal south direction for this SE-facing beach. Rain drops to 3.45 mm/day, air temperatures stay near 25.8°C, and water temperature is 28.2°C. It is a trade-off: clean surface, but less ideal swell direction.