Llangrannog Surf Stats

The rose diagram illustrates the variation of swells directed at Llangrannog through a typical May and is based upon 3437 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the optimum grid node based on what we know about Llangrannog. In this particular case the best grid node is 38 km away (24 miles). The rose diagram shows the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but lacks direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These happened 57% of the time. Green and yellow show 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 often that size swell occurs. The diagram indicates that the prevailing swell direction, shown by the biggest spokes, was SW, whereas the the most common wind blows from the WSW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Llangrannog and away from the coast. We lump these in with the no surf category of the bar chart. To simplify things we don't show these in the rose plot. Because wind determines whether or not waves are clean enough to surf at Llangrannog, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. Over an average May, swells large enough to cause surfable waves at Llangrannog run for about 14% of the time.

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