Llantwit Major Surf Stats

This picture illustrates the variation of swells directed at Llantwit Major through an average June, based on 3505 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coast so we have chosen the best grid node based on what we know about Llantwit Major. In the case of Llantwit Major, the best grid node is 36 km away (22 miles). The rose diagram describes 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 were forecast 38% of the time. Green and yellow represent increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. In both graphs, the area of any colour is proportional to how commonly that size swell occurs. The diagram implies that the dominant swell direction, shown by the longest spokes, was WSW (which was the same as the most common wind direction). Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Llantwit Major and offshore. We lump these in with the no surf category of the bar chart. To avoid confusion we don't show these in the rose plot. Because wind determines whether or not waves are clean enough to surf at Llantwit Major, you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical June, swells large enough to cause surfable waves at Llantwit Major run for about 14% of the time.

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