This image shows only the swells directed at Pointe des Chateaux that coincided with light winds or offshore conditions over a normal September. It is based on 1680 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. Green and yellow represent increasing swell sizes and red shows 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 prevailing swell direction, shown by the largest spokes, was NE, whereas the the prevailing wind blows from the E. The chart at the bottom shows the same thing but without direction information. For example, swells larger than 1.5 feet (0.5m) coincided with good wind conditions 12% of the time, equivalent to 4 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal September but 6% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 6%, equivalent to (2 days). Taking into account the proportion of these swells that coincided with predicted offshore winds, and given the fact that Pointe des Chateaux is exposed to open water swells, we think that that clean surf can be found at Pointe des Chateaux about 12% of the time and that surf is messed up by onshore wind 51% of the time. This is means that we expect 19 days with waves in a typical September, of which 4 days should be clean enough to surf.
IMPORTANT: Beta version feature! Swell heights are open water values from NWW3. There is no attempt to model near-shore effects. Coastal wave heights will generally be less, especially if the break does not have unobstructed exposure to the open ocean.