Black Rock Surf Stats

The graph illustrates the range of swells directed at Black Rock over a normal September and is based upon 3360 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 best grid node based on what we know about Black Rock, and at Black Rock the best grid node is 44 km away (27 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 show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These occurred only 64% of the time. Green and yellow show increasing swell sizes and red illustrates largest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell happens. The diagram indicates that the most common swell direction, shown by the largest spokes, was NE (which was the same as the most common wind direction). Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Black Rock and away from the coast. We lump these in 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 Black Rock, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. During a typical September, swells large enough to cause surfable waves at Black Rock run for about 36% of the time.

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