Aan Golf Statistieken, Herfst: Golven met Licht of Offshore Winden
This image shows only the swells directed at Aan that coincided with light winds or offshore conditions through a typical southern hemisphere autumn. It is based on 6580 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 illustrates highest swells greater than >3m (>10ft). In each graph, 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 biggest spokes, was SW, whereas the the dominant wind blows from the ESE. 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 28% of the time, equivalent to 25 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal southern hemisphere autumn but 5% of the time we expect swell in the range 2-3m (6.5-10ft) 5%, equivalent to (5 days). Taking into account the ratio of these swells that coincided with predicted offshore winds, and given the fact that Aan is slightly protected from open water swells, we estimate that clean surf can be found at Aan about 28% of the time and that surf is spoilt by onshore wind 53% of the time. This is means that we expect 74 days with waves in a typical southern hemisphere autumn, 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.