This image shows only the swells directed at El Segundo Beach Jetty that coincided with light winds or offshore conditions over a normal northern hemisphere autumn. It is based on 5144 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 largest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how commonly that size swell was forecast.
The diagram implies that the most common swell direction, shown by the largest spokes, was SW, whereas the the most common wind blows from the WNW. 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 46% of the time, equivalent to 42 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal northern hemisphere autumn but 5% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 5%, equivalent to (5 days). Taking into account the proportion of these swells that coincided with forecast offshore winds we think that that clean surf can be found at El Segundo Beach Jetty about 46% of the time and that surf is spoilt by onshore wind 45% of the time. This is means that we expect 83 days with waves in a typical northern hemisphere autumn, of which 42 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.