Arrieta Swell Statistics, August: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Arrieta that coincided with light winds or offshore conditions through a typical August and is based upon 2480 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 illustrate increasing swell sizes and red represents the biggest swells, greater than >3m (>10ft). In either 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 N, whereas the the prevailing wind blows from the NNE. 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 0.1% of the time, equivalent to 0 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal August. Taking into account the ratio of these swells that coincided with forecast offshore winds, and given the fact that Arrieta is quite sheltered from open water swells, we think that that clean surf can be found at Arrieta about 0.1% of the time and that surf is spoilt by onshore wind 22% of the time. This is means that we expect 7 days with waves in a typical August, 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.