Viana do Castelo Surf Stats

The figure illustrates the combination of swells directed at Viana do Castelo through an average April, based on 3360 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and 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 describes 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 5% of the time. Green and yellow illustrate increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how commonly that size swell was forecast. The diagram implies that the most common swell direction, shown by the longest spokes, was WNW, whereas the the most common 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 group 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 Viana do Castelo, you can load a different image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical April, swells large enough to cause good for surfing waves at Viana do Castelo run for about 95% of the time.

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