Algarrobo Swell Statistics, September: Surf with Light or Offshore Winds
This image shows only the swells directed at Algarrobo that coincided with light winds or offshore conditions over a normal 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 represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. Green and yellow represent increasing swell sizes and red illustrates the largest swells, greater than >3m (>10ft). In both graphs, 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 WSW, whereas the the most common wind blows from the SSW. 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 14% of the time, equivalent to 4 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal September but 8% of the time we expect swell in the range 2-3m (6.5-10ft) 8%, equivalent to (2 days). Taking into account the ratio of these swells that coincided with predicted offshore winds, and given the fact that Algarrobo is exposed to open water swells, we calculate that clean surf can be found at Algarrobo about 14% of the time and that surf is messed up by onshore wind 86% of the time. This is means that we expect 30 days with waves in a typical September, of which 4 days should be clean enough to surf.
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.