Coral Heads Surf Stats

This picture shows the variation of swells directed at Coral Heads 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 and surf right at the shore so we have chosen the optimum grid node based on what we know about Coral Heads. In this particular case the best grid node is 31 km away (19 miles). The rose diagram shows 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 25% of the time. Green and yellow illustrate increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In either graph, the area of any colour is proportional to how frequently that size swell was forecast. The diagram suggests that the dominant swell direction, shown by the longest spokes, was SE, whereas the the prevailing wind blows from the ENE. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Coral Heads and offshore. We combine 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 Coral Heads, you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical April, swells large enough to cause surfable waves at Coral Heads run for about 75% of the time.

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