Barra de Guaratiba Surf Stats

This picture describes the variation of swells directed at Barra de Guaratiba through a typical August, based on 3574 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 optimum grid node based on what we know about Barra de Guaratiba, and at Barra de Guaratiba the best grid node is 59 km away (37 miles). The rose diagram describes the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but lacks 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 34% of the time. Green and yellow illustrate increasing swell sizes and red illustrates the highest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how frequently that size swell occurs. The diagram suggests that the prevailing swell direction, shown by the longest spokes, was S, whereas the the dominant wind blows from the ENE. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Barra de Guaratiba and offshore. We combine these 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 Barra de Guaratiba, you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average August, swells large enough to cause good for surfing waves at Barra de Guaratiba run for about 41% of the time.

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