The rose diagram shows only the swells directed at The Dump that coincided with light winds or offshore conditions through a typical December. It is based on 1736 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 red illustrates the largest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how often that size swell happens.
The diagram indicates that the dominant swell direction, shown by the largest spokes, was W, whereas the the most common wind blows from the SE. 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 54% of the time, equivalent to 16 days. Expect open water swells to exceed >3m (>10ft) 16% of the time (5 days). Taking into account the ratio of these swells that coincided with forecast offshore winds we estimate that clean surf can be found at The Dump about 54% of the time and that surf is spoilt by onshore wind 37% of the time. This is means that we expect 27 days with waves in a typical December, of which 16 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.