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Onekaka Swell Statistics, April: All Swell – Any Wind

This chart illustrates the range of swells directed at Onekaka through an average April and is based upon 2880 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and surf right at the shore so we have chosen the most applicable grid node based on what we know about Onekaka. In this particular case the best grid node is 37 km away (23 miles).

The rose diagram describes the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but without direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These were forecast only 97% of the time. Green and yellow show increasing swell sizes and red illustrates largest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how frequently that size swell was forecast.

The diagram suggests that the dominant swell direction, shown by the longest spokes, was E, whereas the the most common wind blows from the W. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Onekaka and out to sea. We lump these in with the no surf category of the bar chart. To simplify things we don't show these in the rose graph. Because wind determines whether or not waves are good for surfing at Onekaka, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical April, swells large enough to cause clean enough to surf waves at Onekaka run for about 3% of the time.

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.