China Beach Surf Stats

The rose diagram illustrates the range of swells directed at China Beach through an average April. It is based on 3360 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the coastline so we have chosen the optimum grid node based on what we know about China Beach. In this particular case the best grid node is 67 km away (42 miles). The rose diagram shows 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 21% of the time. Green and yellow illustrate increasing swell sizes and red illustrates largest 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 most common swell direction, shown by the longest spokes, was W, whereas the the most common wind blows from the SSW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from China Beach and out to sea. 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 good for surfing at China Beach, you can view an alternative image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical April, swells large enough to cause clean enough to surf waves at China Beach run for about 72% of the time.

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