Aberdaron Swell Statistics, Setembro: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Aberdaron that coincided with light winds or offshore conditions through a typical September. It is based on 2397 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. Green and yellow illustrate increasing swell sizes and red represents highest 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 WSW (which was the same as the dominant wind direction). 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 0.3% of the time, equivalent to 0 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal September. Taking into account the fraction of these swells that coincided with expected offshore winds, and given the fact that Aberdaron is slightly protected from open water swells, we estimate that clean surf can be found at Aberdaron about 0.3% of the time and that surf is blown out by onshore wind 18% of the time. This is means that we expect 5 days with waves in a typical September, of which 0 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.