Nine Mile Reef Surf Stats

The figure shows the variation of swells directed at Nine Mile Reef through a typical April, based on 2880 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the most applicable grid node based on what we know about Nine Mile Reef. In this particular case the best grid node is 50 km away (31 miles). The rose diagram illustrates the distribution of swell sizes and directions, 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 happened only 60% 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 frequently that size swell occurs. The diagram suggests that the prevailing swell direction, shown by the longest spokes, was S (which was the same as the prevailing wind direction). Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Nine Mile Reef and away from the coast. We group these with the no surf category of the bar chart. To keep it simple we don't show these in the rose graph. Because wind determines whether or not waves are clean enough to surf at Nine Mile Reef, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average April, swells large enough to cause surfable waves at Nine Mile Reef run for about 40% of the time.

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