Praia Grande Surf Stats

The rose diagram illustrates the variation of swells directed at Praia Grande through an average July. It is based on 3720 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the optimum grid node based on what we know about Praia Grande. In this particular case the best grid node is 46 km away (29 miles). The rose diagram illustrates 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 3% of the time. Green and yellow represent increasing swell sizes and red represents the largest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell was forecast. The diagram suggests that the prevailing swell direction, shown by the biggest spokes, was SSE, whereas the the most common wind blows from the ENE. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Praia Grande and out to sea. We group these with the no surf category of the bar chart. To keep it simple we don't show these in the rose graph. Because wind determines whether or not waves are good for surfing at Praia Grande, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical July, swells large enough to cause clean enough to surf waves at Praia Grande run for about 97% of the time.

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