Kanaha Swell Statistics, April: Surf with Light or Offshore Winds
This image shows only the swells directed at Kanaha that coincided with light winds or offshore conditions over a normal April and is based upon 1920 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 biggest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell happens.
The diagram indicates that the most common swell direction, shown by the longest spokes, was NNE, 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 41% of the time, equivalent to 12 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal April but 16% of the time we expect swell in the range 2-3m (6.5-10ft) 16%, equivalent to (5 days). Taking into account the ratio of these swells that coincided with expected offshore winds we estimate that clean surf can be found at Kanaha about 41% of the time and that surf is blown out by onshore wind 18% of the time. This is means that we expect 18 days with waves in a typical April, of which 12 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.