Zanzibar Surf Stats

This chart illustrates the combination of swells directed at Zanzibar through an average April and is based upon 3360 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and surf right at the coast so we have chosen the best grid node based on what we know about Zanzibar. In this particular case the best grid node is 35 km away (22 miles). The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but lacks direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These were forecast only 84% of the time. Green and yellow illustrate increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. In either graph, the area of any colour is proportional to how commonly that size swell was forecast. The diagram implies that the prevailing swell direction, shown by the largest spokes, was N, whereas the the most common wind blows from the E. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Zanzibar and offshore. 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 Zanzibar, you can load a different image 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 surfable waves at Zanzibar run for about 1.0% of the time.

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