This image shows only the swells directed at Waipio Valley 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 illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. Green and yellow show increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In both graphs, the area of any colour is proportional to how often that size swell was forecast.
The diagram indicates that the most common swell direction, shown by the biggest spokes, was N, whereas the the prevailing wind blows from the E. 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 0% of the time, equivalent to 0 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal August. Taking into account the proportion of these swells that coincided with predicted offshore winds we think that that clean surf can be found at Waipio Valley about 0% of the time and that surf is messed up by onshore wind 10% of the time. This is means that we expect 3 days with waves in a typical August, of which 0 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.