St Jean de Monts Surf Stats

This image illustrates the combination of swells directed at St Jean de Monts through an average April, based on 3360 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 optimum grid node based on what we know about St Jean de Monts. In the case of St Jean de Monts, the best grid node is 31 km away (19 miles). The rose diagram shows the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These happened only 13% of the time. Green and yellow show increasing swell sizes and red illustrates the largest 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 prevailing swell direction, shown by the biggest spokes, was W, whereas the the most common wind blows from the N. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from St Jean de Monts and away from the coast. We lump these in with the no surf category of the bar chart. To simplify things we don't show these in the rose plot. Because wind determines whether or not waves are clean enough to surf 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. In a typical April, swells large enough to cause surfable waves at St Jean de Monts run for about 87% of the time.

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