Grunters Surf Stats

The figure shows the combination of swells directed at Grunters through a typical September and is based upon 3360 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the most applicable grid node based on what we know about Grunters, and at Grunters the best grid node is 46 km away (29 miles). The rose diagram describes the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but without direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These happened only 0.5% of the time. Green and yellow represent increasing swell sizes and red shows biggest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell occurs. The diagram implies that the most common swell direction, shown by the largest spokes, was SW, whereas the the prevailing wind blows from the WSW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Grunters and away from the coast. We lump these in with the no surf category of the bar chart. To keep it simple we don't show these in the rose diagram. Because wind determines whether or not waves are surfable at Grunters, 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 September, swells large enough to cause good for surfing waves at Grunters run for about 100% of the time.

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