Treachery Head Surf Stats

The graph describes the range of swells directed at Treachery Head through a typical August and is based upon 3472 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the best grid node based on what we know about Treachery Head, and at Treachery Head the best grid node is 7 km away (4 miles). The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred only 17% of the time. Green and yellow represent increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In each graph, 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 SE, whereas the the dominant wind blows from the W. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Treachery Head and out to sea. We combine these with the no surf category of the bar chart. To simplify things we don't show these in the rose diagram. Because wind determines whether or not waves are surfable at Treachery Head, you can view an alternative image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. Over an average August, swells large enough to cause good for surfing waves at Treachery Head run for about 83% of the time.

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