This image shows only the swells directed at San Gregorio State Beach 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 represent increasing swell sizes and red represents highest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how often that size swell occurs.
The diagram indicates that the dominant swell direction, shown by the largest spokes, was SW, whereas the the dominant 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 18% of the time, equivalent to 6 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal July but 8% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 8%, equivalent to (2 days). Taking into account the ratio of these swells that coincided with expected offshore winds, and given the fact that San Gregorio State Beach is exposed to open water swells, we calculate that clean surf can be found at San Gregorio State Beach about 18% of the time and that surf is messed up by onshore wind 25% of the time. This is means that we expect 13 days with waves in a typical July, of which 6 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.