Ballycastle Surf Stats

The rose diagram illustrates the variation of swells directed at Ballycastle over a normal May. It is based on 3192 NWW3 model predictions since 2008 (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 Ballycastle. In this particular case the best grid node is 36 km away (22 miles). The rose diagram describes the distribution of swell sizes and directions, 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 were forecast 36% of the time. Green and yellow represent increasing swell sizes and red represents largest 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 prevailing swell direction, shown by the longest spokes, was WNW, whereas the the most common wind blows from the SSW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Ballycastle and offshore. We group these 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 clean enough to surf at Ballycastle, 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 May, swells large enough to cause surfable waves at Ballycastle run for about 16% of the time.

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