Mana Island Surf Stats

This picture shows the range of swells directed at Mana Island through an average September, based on 3358 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the optimum grid node based on what we know about Mana Island. In the case of Mana Island, the best grid node is 25 km away (16 miles). The rose diagram describes the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing without direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These were forecast only 52% of the time. Green and yellow show increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In both graphs, 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 NW (which was the same as the prevailing wind direction). Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Mana Island and offshore. We combine 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 good for surfing at Mana Island, you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical September, swells large enough to cause clean enough to surf waves at Mana Island run for about 48% of the time.

read more