Llanddwyn Island Surf Stats

The graph shows the variation of swells directed at Llanddwyn Island over a normal September and is based upon 3358 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 Llanddwyn Island, and at Llanddwyn Island the best grid node is 16 km away (10 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 illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred 54% of the time. Green and yellow illustrate increasing swell sizes and red represents biggest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how often that size swell was forecast. The diagram indicates that the dominant swell direction, shown by the largest spokes, was SW, whereas the the prevailing wind blows from the WSW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Llanddwyn Island 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 diagram. Because wind determines whether or not waves are surfable at Llanddwyn Island, you can load a different image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. During a typical September, swells large enough to cause good for surfing waves at Llanddwyn Island run for about 46% of the time.

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