JD Reef Surf Stats

This chart shows the range of swells directed at JD Reef through a typical April. It is based on 3360 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the optimum grid node based on what we know about JD Reef. In the case of JD Reef, the best grid node is 26 km away (16 miles). The rose diagram illustrates the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but lacks 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 occurred only 25% of the time. Green and yellow represent increasing swell sizes and red illustrates biggest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell happens. The diagram implies that the dominant swell direction, shown by the largest spokes, was SE, whereas the the prevailing wind blows from the S. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from JD Reef and away from the coast. We combine these with the no surf category of the bar chart. To simplify things we don't show these in the rose plot. Because wind determines whether or not waves are surfable at JD Reef, you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. Over an average April, swells large enough to cause good for surfing waves at JD Reef run for about 75% of the time.

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