This image shows only the swells directed at Lackan Bay that coincided with light winds or offshore conditions over a normal December 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 represent increasing swell sizes and red represents biggest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell was forecast.
The diagram suggests that the most common swell direction, shown by the biggest spokes, was WNW, whereas the the prevailing wind blows from the SW. 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 27% of the time, equivalent to 8 days. Expect open water swells to exceed >3m (>10ft) 17% of the time (5 days). Taking into account the fraction of these swells that coincided with predicted offshore winds, and given the fact that Lackan Bay is slightly protected from open water swells, we think that that clean surf can be found at Lackan Bay about 27% of the time and that surf is blown out by onshore wind 26% of the time. This is means that we expect 16 days with waves in a typical December, of which 8 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.