Black Rock Surf Stats

This chart shows the variation of swells directed at Black Rock over a normal January. It is based on 3364 NWW3 model predictions since 2007 (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 Black Rock, and at Black Rock the best grid node is 44 km away (27 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 39% of the time. Green and yellow illustrate increasing swell sizes and red represents biggest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell was forecast. The diagram implies that the most common swell direction, shown by the largest spokes, was ENE (which was the same as the prevailing wind direction). Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Black Rock and offshore. We lump these in 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 Black Rock, 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 January, swells large enough to cause surfable waves at Black Rock run for about 61% of the time.

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