Otago Peninsula - Sandfly Bay Surf Stats

The graph describes the range of swells directed at Otago Peninsula - Sandfly Bay over a normal July. It is based on 3472 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coast so we have chosen the best grid node based on what we know about Otago Peninsula - Sandfly Bay, and at Otago Peninsula - Sandfly Bay the best grid node is 16 km away (10 miles). The rose diagram shows the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but without 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 32% of the time. Green and yellow represent increasing swell sizes and red represents the highest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell was forecast. The diagram implies that the most common swell direction, shown by the biggest spokes, was S, whereas the the dominant wind blows from the NW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Otago Peninsula - Sandfly Bay and offshore. We lump these in 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 Otago Peninsula - Sandfly Bay, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical July, swells large enough to cause good for surfing waves at Otago Peninsula - Sandfly Bay run for about 68% of the time.

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