Saco da Mãe Surf Stats

The graph describes the variation of swells directed at Saco da Mãe through an average September, based on 3360 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the shore so we have chosen the most applicable grid node based on what we know about Saco da Mãe, and at Saco da Mãe the best grid node is 10 km away (6 miles). The rose diagram shows 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 happened only 10% of the time. Green and yellow show increasing swell sizes and highest 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 dominant swell direction, shown by the longest spokes, was ESE, whereas the the dominant 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 Saco da Mãe and out to sea. We group these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose diagram. Because wind determines whether or not waves are good for surfing at Saco da Mãe, you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical September, swells large enough to cause clean enough to surf waves at Saco da Mãe run for about 18% of the time.

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