Van Stadens Mouth Surf Stats

The figure describes the variation of swells directed at Van Stadens Mouth through a typical May. It is based on 3440 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the coast so we have chosen the best grid node based on what we know about Van Stadens Mouth. In the case of Van Stadens Mouth, the best grid node is 23 km away (14 miles). The rose diagram shows the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but lacks 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 5% of the time. Green and yellow represent increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how often that size swell happens. The diagram indicates that the prevailing swell direction, shown by the longest spokes, was S, whereas the the dominant wind blows from the WNW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Van Stadens Mouth and away from the coast. We group these with the no surf category of the bar chart. To keep it simple we don't show these in the rose graph. Because wind determines whether or not waves are clean enough to surf at Van Stadens Mouth, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average May, swells large enough to cause surfable waves at Van Stadens Mouth run for about 95% of the time.

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