This image shows only the swells directed at Horseshoe that coincided with light winds or offshore conditions through a typical 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 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 shows highest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how commonly that size swell occurs.
The diagram implies that the dominant swell direction, shown by the longest spokes, was WSW, 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 14% of the time, equivalent to 13 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal northern hemisphere summer. Taking into account the ratio of these swells that coincided with expected offshore winds, and given the fact that Horseshoe is exposed to open water swells, we think that that clean surf can be found at Horseshoe about 14% of the time and that surf is messed up by onshore wind 11% of the time. This is means that we expect 23 days with waves in a typical northern hemisphere summer, of which 13 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.