Belle Ile Surf Stats

The rose diagram describes the range of swells directed at Belle Ile through a typical May and is based upon 3440 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the optimum grid node based on what we know about Belle Ile. In this particular case the best grid node is 40 km away (25 miles). The rose diagram shows the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but without direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These occurred only 48% of the time. Green and yellow illustrate increasing swell sizes and red illustrates highest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell occurs. The diagram implies that the most common swell direction, shown by the longest spokes, was WSW, whereas the the dominant wind blows from the NNW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Belle Ile and away from the coast. We group these 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 clean enough to surf at Belle Ile, 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 May, swells large enough to cause surfable waves at Belle Ile run for about 52% of the time.

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