Nantasket Beach Surf Stats

The rose diagram shows the combination of swells directed at Nantasket Beach over a normal May and is based upon 2838 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and surf right at the shore so we have chosen the most applicable grid node based on what we know about Nantasket Beach. In this particular case the best grid node is 38 km away (24 miles). The rose diagram describes the distribution of swell sizes and directions, 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 were forecast only 63% of the time. Green and yellow show increasing swell sizes and red shows 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 largest spokes, was ENE, 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 Nantasket Beach 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 diagram. Because wind determines whether or not waves are clean enough to surf at Nantasket Beach, you can view an alternative image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. During a typical May, swells large enough to cause surfable waves at Nantasket Beach run for about 37% of the time.

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