Kahana Bay Surf Stats

The graph describes the combination of swells directed at Kahana Bay through a typical May, based on 3440 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the coast so we have chosen the best grid node based on what we know about Kahana Bay. In this particular case the best grid node is 39 km away (24 miles). The rose diagram shows the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred only 36% of the time. Green and yellow illustrate increasing swell sizes and red illustrates the highest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how frequently that size swell happens. The diagram suggests that the dominant swell direction, shown by the longest spokes, was NE, whereas the the dominant wind blows from the ENE. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Kahana Bay and away from the coast. We lump these in with the no surf category of the bar chart. To avoid confusion we don't show these in the rose graph. Because wind determines whether or not waves are good for surfing at Kahana Bay, you can load a different image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. Over an average May, swells large enough to cause clean enough to surf waves at Kahana Bay run for about 64% of the time.

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