Sao Joao Surf Stats

This picture shows the combination of swells directed at Sao Joao through an average September and is based upon 3360 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coast so we have chosen the optimum grid node based on what we know about Sao Joao, and at Sao Joao the best grid node is 27 km away (17 miles). The rose diagram illustrates the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred only 18% of the time. Green and yellow show increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In each 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 biggest spokes, was WNW, whereas the the prevailing wind blows from the NW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Sao Joao and away from the coast. We lump these in with the no surf category of the bar chart. To simplify things we don't show these in the rose diagram. Because wind determines whether or not waves are surfable at Sao Joao, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical September, swells large enough to cause good for surfing waves at Sao Joao run for about 82% of the time.

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