Cape St Francis Surf Stats

This picture shows the range of swells directed at Cape St Francis through an average July. It is based on 3720 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the most applicable grid node based on what we know about Cape St Francis. In the case of Cape St Francis, the best grid node is 37 km away (23 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 represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These were forecast only 96% of the time. Green and yellow show increasing swell sizes and red illustrates biggest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell occurs. The diagram implies that the prevailing swell direction, shown by the largest spokes, was ESE, whereas the the prevailing wind blows from the WNW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Cape St Francis and offshore. We combine these 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 clean enough to surf at Cape St Francis, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical July, swells large enough to cause surfable waves at Cape St Francis run for about 4% of the time.

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