Riet River Swell Statistics, Summer: Surf with Light or Offshore Winds
This image shows only the swells directed at Riet River that coincided with light winds or offshore conditions over a normal southern hemisphere summer. It is based on 5736 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 represent increasing swell sizes and red represents largest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the most common swell direction, shown by the largest 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 27% of the time, equivalent to 25 days. Expect open water swells to exceed >3m (>10ft) 4% of the time (4 days). Taking into account the fraction of these swells that coincided with expected 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 27% of the time and that surf is spoilt by onshore wind 48% of the time. This is means that we expect 68 days with waves in a typical southern hemisphere summer, of which 25 days should be surfable.
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.