This image shows only the swells directed at S-Turns that coincided with light winds or offshore conditions over a normal December. It is based on 1736 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. Green and yellow illustrate increasing swell sizes and red shows highest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell was forecast.
The diagram indicates that the most common swell direction, shown by the biggest spokes, was ESE, whereas the the dominant wind blows from the NW. The chart at the bottom shows the same thing but without direction information. For example, swells larger than 1.5 feet (0.5m) coincided with good wind conditions 16% of the time, equivalent to 5 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal December but 5% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 5%, equivalent to (2 days). Taking into account the proportion of these swells that coincided with predicted offshore winds we estimate that clean surf can be found at S-Turns about 16% of the time and that surf is spoilt by onshore wind 28% of the time. This is means that we expect 13 days with waves in a typical December, of which 5 days should be clean enough to surf.
IMPORTANT: Beta version feature! Swell heights are open water values from NWW3. There is no attempt to model near-shore effects. Coastal wave heights will generally be less, especially if the break does not have unobstructed exposure to the open ocean.