This image shows only the swells directed at Mauvaise Greve that coincided with light winds or offshore conditions through a typical January and is based upon 1728 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. Green and yellow show increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. In either graph, the area of any colour is proportional to how frequently that size swell was forecast.
The diagram suggests that the dominant swell direction, shown by the largest spokes, was W, whereas the the most common wind blows from the WSW. 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 29% of the time, equivalent to 9 days. Open water swells exceeding >3m (>10ft) only occur 3% of the time in a typical January, equivalent to just one day but 14% of the time we expect swell in the range 2-3m (6.5-10ft) 14%, equivalent to (4 days). Taking into account the ratio of these swells that coincided with expected offshore winds we estimate that clean surf can be found at Mauvaise Greve about 29% of the time and that surf is messed up by onshore wind 61% of the time. This is means that we expect 28 days with waves in a typical January, of which 9 days should be surfable.
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.