This image shows only the swells directed at Mauvaise Greve that coincided with light winds or offshore conditions through a typical 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 illustrates the largest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell happens.
The diagram indicates that the prevailing swell direction, shown by the biggest spokes, was W (which was the same as the most common wind direction). 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 23% of the time, equivalent to 7 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal September but 10% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 10%, equivalent to (3 days). Taking into account the proportion of these swells that coincided with forecast offshore winds we think that that clean surf can be found at Mauvaise Greve about 23% of the time and that surf is blown out by onshore wind 63% of the time. This is means that we expect 26 days with waves in a typical September, of which 7 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.