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 5478 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 largest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the dominant 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 proportion of these swells that coincided with expected offshore winds, and given the fact that Riet River is exposed to open water swells, we calculate that clean surf can be found at Riet River about 27% of the time and that surf is messed up by onshore wind 47% of the time. This is means that we expect 67 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.