Black Rocks Surf Stats

The graph shows the combination of swells directed at Black Rocks through an average September, based on 3360 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the coast so we have chosen the most applicable grid node based on what we know about Black Rocks. In the case of Black Rocks, the best grid node is 23 km away (14 miles). The rose diagram illustrates 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 93% of the time. Green and yellow represent increasing swell sizes and red illustrates the biggest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how frequently that size swell was forecast. The diagram suggests that the prevailing swell direction, shown by the largest spokes, was SSE, whereas the the prevailing wind blows from the SW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Black Rocks and out to sea. We group these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose graph. Because wind determines whether or not waves are good for surfing at Black Rocks, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical September, swells large enough to cause clean enough to surf waves at Black Rocks run for about 7% of the time.

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