This image shows only the swells directed at San Onofre that coincided with light winds or offshore conditions over a normal July. It is based on 1736 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 show increasing swell sizes and red illustrates the biggest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how commonly that size swell happens.

The diagram implies that the prevailing swell direction, shown by the largest spokes, was SSW, whereas the the prevailing wind blows from the W. 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 52% of the time, equivalent to 16 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal July. Taking into account the proportion of these swells that coincided with predicted offshore winds, and given the fact that San Onofre is exposed to open water swells, we estimate that clean surf can be found at San Onofre about 52% of the time and that surf is messed up by onshore wind 44% of the time. This is means that we expect 30 days with waves in a typical July, of which 16 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.