Ranganunu Harbour Surf Stats

This image shows the range of swells directed at Ranganunu Harbour over a normal May. It is based on 3440 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the optimum 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 describes 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 were forecast only 71% of the time. Green and yellow represent 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 commonly that size swell occurs. The diagram implies that the dominant swell direction, shown by the longest spokes, was NE, whereas the the prevailing wind blows from the SW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Ranganunu Harbour and out to sea. We group these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose plot. Because wind determines whether or not waves are surfable at Ranganunu Harbour, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical May, swells large enough to cause good for surfing waves at Ranganunu Harbour run for about 27% of the time.

read more