Plum Island Surf Stats

This chart shows the variation of swells directed at Plum Island over a normal July. It is based on 3720 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coast so we have chosen the best grid node based on what we know about Plum Island, and at Plum Island the best grid node is 34 km away (21 miles). The rose diagram illustrates 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 occurred 30% of the time. Green and yellow illustrate increasing swell sizes and red represents biggest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell was forecast. The diagram indicates that the most common swell direction, shown by the longest spokes, was ESE, whereas the the prevailing wind blows from the SSW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Plum Island and offshore. We group these 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 Plum Island, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. During a typical July, swells large enough to cause good for surfing waves at Plum Island run for about 70% of the time.

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