Mahanga Point Surf Stats

The figure shows the range of swells directed at Mahanga Point over a normal September. It is based on 3360 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the shore so we have chosen the best grid node based on what we know about Mahanga Point. In this particular case the best grid node is 9 km away (6 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 71% of the time. Green and yellow show increasing swell sizes and red represents the biggest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how frequently that size swell occurs. The diagram suggests that the dominant swell direction, shown by the largest spokes, was ENE, whereas the the prevailing wind blows from the WNW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Mahanga Point and away from the coast. We combine these 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 Mahanga Point, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. During a typical September, swells large enough to cause good for surfing waves at Mahanga Point run for about 29% of the time.

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