Plum Island Surf Stats

The figure shows the variation of swells directed at Plum Island through a typical May. It is based on 3440 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the coastline so we have chosen the best grid node based on what we know about Plum Island. In the case of Plum Island, the best grid node is 34 km away (21 miles). The rose diagram illustrates the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks 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 29% of the time. Green and yellow show increasing swell sizes and red represents the biggest swells, greater than >3m (>10ft). In either 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 biggest spokes, was ESE, whereas the the prevailing wind blows from the SSW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Plum Island and away from the coast. 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 good for surfing 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. Over an average May, swells large enough to cause clean enough to surf waves at Plum Island run for about 71% of the time.

read more