Ala Moana Swell Statistics, All Year: Surf with Light or Offshore Winds
This image shows only the swells directed at Ala Moana that coincided with light winds or offshore conditions through a typical year. It is based on 28044 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 illustrates largest 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 SSW, whereas the the most common wind blows from the S. 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 5% of the time, equivalent to 18 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal year but 1.1% of the time we expect swell in the range 2-3m (6.5-10ft) 1.1%, equivalent to (4 days). Taking into account the proportion of these swells that coincided with forecast offshore winds, and given the fact that Ala Moana is exposed to open water swells, we think that that clean surf can be found at Ala Moana about 5% of the time and that surf is messed up by onshore wind 95% of the time. This is means that we expect 365 days with waves in a typical year, of which 18 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.