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Zanzibar ratings
Quality on a good day: 3.0
Consistency of Surf: 1.0
Difficulty Level: 3.0
Crowds: 4.0

Overall: 3.2

See all 18 ratings

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Surf Report Feed

Zanzibar Swell Statistics, July: All Swell – Any Wind

The rose diagram shows the variation of swells directed at Zanzibar over a normal July, based on 2976 NWW3 model predictions since 2006 (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 Zanzibar, and at Zanzibar the best grid node is 35 km away (22 miles).

The rose diagram describes the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing without 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 100% of the time. Green and yellow show increasing swell sizes and red illustrates the biggest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how often that size swell was forecast.

The diagram indicates that the prevailing swell direction, shown by the longest spokes, was N, whereas the the prevailing wind blows from the E. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Zanzibar and out to sea. We combine these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose plot. Because wind determines whether or not waves are clean enough to surf at Zanzibar, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical July, swells large enough to cause surfable waves at Zanzibar run for about 0% 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.