13th Beach • Statistics for December

December: Summer's Onshore Grip

December closes the year the same way it starts - with summer seabreezes and a swing back to shorter-period, lower-energy surf. The average wave height is 5ft (1.5m) and the average period is 11.1s, the lowest of the year. Swell direction remains SW-SSW dominated, with SW at 48% and SSW at 24%, but the real problem is wind. Onshore SSE-SW winds account for a full 45.8% of the wind rose, while offshore flow from the N, NNE, NE and NNW quadrant is a scarce 11.5%, and ideal wind is only 14% - tied for the lowest of the year. The daily S to SSE seabreeze is relentless, building through the afternoon and chopping out the lineup. That said, there is still plenty of long-period groundswell around; the quality simply hinges on the morning offshore window. Water temp is a warm 19.1°C and air temps average 16.2°C, so for those willing to dawn patrol, December can offer fun, uncrowded summer surf on that rare glassy early session.