Ranganunu Harbour Surf Stats

The rose diagram illustrates the combination of swells directed at Ranganunu Harbour through an average July and is based upon 3720 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the most applicable grid node based on what we know about Ranganunu Harbour. In the case of Ranganunu Harbour, the best grid node is 49 km away (30 miles). The rose diagram shows the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but lacks direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These occurred only 76% of the time. Green and yellow represent increasing swell sizes and largest 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 dominant swell direction, shown by the longest spokes, was NE, whereas the the most common wind blows from the WSW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Ranganunu Harbour and offshore. We lump these in with the no surf category of the bar chart. To avoid confusion we don't show these in the rose diagram. Because wind determines whether or not waves are surfable at Ranganunu Harbour, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical July, swells large enough to cause good for surfing waves at Ranganunu Harbour run for about 23% of the time.

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