Agucadoura Swell Statistics, Setembro: Surf with Light or Offshore Winds
This image shows only the swells directed at Agucadoura that coincided with light winds or offshore conditions through a typical September. It is based on 2400 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 show increasing swell sizes and red illustrates the largest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell occurs.
The diagram implies that the dominant swell direction, shown by the longest spokes, was WNW, whereas the the most common wind blows from the NNW. 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 29% of the time, equivalent to 9 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal September but 9% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 9%, equivalent to (3 days). Taking into account the proportion of these swells that coincided with predicted offshore winds, and given the fact that Agucadoura is exposed to open water swells, we calculate that clean surf can be found at Agucadoura about 29% of the time and that surf is messed up by onshore wind 61% of the time. This is means that we expect 27 days with waves in a typical September, of which 9 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.