This image shows only the swells directed at Kerloch that coincided with light winds or offshore conditions over a normal northern hemisphere summer. It is based on 5066 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 represent increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. In both graphs, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the dominant swell direction, shown by the longest spokes, was W, 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 13% of the time, equivalent to 12 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal northern hemisphere summer 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 fraction of these swells that coincided with forecast offshore winds, and given the fact that Kerloch is exposed to open water swells, we calculate that clean surf can be found at Kerloch about 13% of the time and that surf is blown out by onshore wind 44% of the time. This is means that we expect 52 days with waves in a typical northern hemisphere summer, of which 12 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.