This image shows only the swells directed at Riet River that coincided with light winds or offshore conditions through a typical southern hemisphere summer. It is based on 5048 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 largest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell was forecast.
The diagram implies that the dominant swell direction, shown by the biggest spokes, was SSW, whereas the the most common wind blows from the SE. 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 26% of the time, equivalent to 24 days. Expect open water swells to exceed >3m (>10ft) 4% of the time (4 days). Taking into account the proportion of these swells that coincided with predicted offshore winds, and given the fact that Riet River is exposed to open water swells, we estimate that clean surf can be found at Riet River about 26% of the time and that surf is spoilt by onshore wind 48% of the time. This is means that we expect 67 days with waves in a typical southern hemisphere summer, of which 24 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.