This image shows only the swells directed at Fort Point that coincided with light winds or offshore conditions through a typical August and is based upon 1736 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 red represents the largest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell happens.
The diagram suggests that the dominant swell direction, shown by the largest spokes, was WNW (which was the same as the most common wind direction). 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 3% of the time, equivalent to 1 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal August but 15% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 15%, equivalent to (5 days). Taking into account the proportion of these swells that coincided with expected offshore winds, and given the fact that Fort Point is quite sheltered from open water swells, we estimate that clean surf can be found at Fort Point about 3% of the time and that surf is blown out by onshore wind 6% of the time. This is means that we expect 3 days with waves in a typical August, of which 1 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.