Sumner Bar Surf Stats

The graph illustrates the range of swells directed at Sumner Bar through a typical June, based on 3266 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the shore so we have chosen the best grid node based on what we know about Sumner Bar, and at Sumner Bar the best grid node is 21 km away (13 miles). The rose diagram illustrates the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing 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 happened only 54% of the time. Green and yellow show increasing swell sizes and red illustrates largest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how often that size swell occurs. The diagram indicates that the prevailing swell direction, shown by the biggest spokes, was E, whereas the the most common wind blows from the WNW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Sumner Bar and offshore. We combine these 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 surfable at Sumner Bar, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. Over an average June, swells large enough to cause good for surfing waves at Sumner Bar run for about 14% of the time.

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