St Agnes Surf Stats

This picture shows the range of swells directed at St Agnes through a typical April, based on 3360 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the best grid node based on what we know about St Agnes, and at St Agnes the best grid node is 28 km away (17 miles). The rose diagram describes the distribution of swell directions and swell sizes, 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 only 14% of the time. Green and yellow illustrate increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In either graph, 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 biggest spokes, was W, whereas the the prevailing wind blows from the NNE. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from St Agnes and away from the coast. We combine these 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 surfable at St Agnes, 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 April, swells large enough to cause good for surfing waves at St Agnes run for about 53% of the time.

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