This image shows only the swells directed at Pwlldu Point that coincided with light winds or offshore conditions over a normal northern hemisphere autumn. It is based on 5142 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. Green and yellow show increasing swell sizes and red illustrates the highest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell was forecast.
The diagram suggests that the most common swell direction, shown by the longest spokes, was WSW, whereas the the dominant wind blows from the SW. 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 7% of the time, equivalent to 6 days. Open water swells exceeding >3m (>10ft) only occur 1.0% of the time in a typical northern hemisphere autumn, equivalent to just one day but 1.9% of the time we expect swell in the range 2-3m (6.5-10ft) 1.9%, equivalent to (2 days). Taking into account the proportion of these swells that coincided with predicted offshore winds, and given the fact that Pwlldu Point is slightly protected from open water swells, we estimate that clean surf can be found at Pwlldu Point about 7% of the time and that surf is spoilt by onshore wind 28% of the time. This is means that we expect 32 days with waves in a typical northern hemisphere autumn, of which 6 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.