Viana do Castelo Surf Stats

The graph shows the variation of swells directed at Viana do Castelo through a typical June. It is based on 3384 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the shore so we have chosen the best grid node based on what we know about Viana do Castelo, and at Viana do Castelo the best grid node is 25 km away (16 miles). The rose diagram shows the distribution of swell directions and swell sizes, 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 5% of the time. Green and yellow illustrate increasing swell sizes and red represents biggest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how often that size swell happens. The diagram indicates that the dominant swell direction, shown by the biggest spokes, was WNW, whereas the the prevailing wind blows from the NW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Viana do Castelo and out to sea. We lump these in with the no surf category of the bar chart. To simplify things we don't show these in the rose graph. Because wind determines whether or not waves are clean enough to surf at Viana do Castelo, 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 June, swells large enough to cause surfable waves at Viana do Castelo run for about 95% of the time.

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