St Jean de Monts Surf Stats

The graph shows the combination of swells directed at St Jean de Monts through a typical September and is based upon 3360 NWW3 model predictions since 2006 (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 St Jean de Monts. In this particular case the best grid node is 31 km away (19 miles). The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred only 16% of the time. Green and yellow represent increasing swell sizes and red shows biggest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell happens. The diagram suggests that the prevailing swell direction, shown by the largest spokes, was W, whereas the the prevailing wind blows from the NNW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from St Jean de Monts 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 St Jean de Monts, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average September, swells large enough to cause good for surfing waves at St Jean de Monts run for about 84% of the time.

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