Porth Beach Surf Stats

The figure shows the combination of swells directed at Porth Beach through a typical September. It is based on 3360 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the coast so we have chosen the best grid node based on what we know about Porth Beach, and at Porth Beach the best grid node is 32 km away (20 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 illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These happened only 12% of the time. Green and yellow show increasing swell sizes and red shows biggest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell happens. The diagram implies that the dominant swell direction, shown by the largest spokes, was W (which was the same as the prevailing wind direction). Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Porth Beach and offshore. We lump these in with the no surf category of the bar chart. To keep it simple we don't show these in the rose diagram. Because wind determines whether or not waves are good for surfing at Porth Beach, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average September, swells large enough to cause clean enough to surf waves at Porth Beach run for about 53% of the time.

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