Saco da Mãe Surf Stats

The graph describes the variation of swells directed at Saco da Mãe through a typical August. It is based on 3472 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 Saco da Mãe, and at Saco da Mãe the best grid node is 10 km away (6 miles). The rose diagram illustrates the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but without direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These were forecast only 14% of the time. Green and yellow illustrate increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In both graphs, 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 biggest spokes, was SE, whereas the the dominant wind blows from the ENE. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Saco da Mãe 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 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. Over an average August, swells large enough to cause clean enough to surf waves at Saco da Mãe run for about 15% of the time.

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