This image shows only the swells directed at Ansteys that coincided with light winds or offshore conditions through a typical July and is based upon 1736 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. Green and yellow represent increasing swell sizes and red represents the biggest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell was forecast.
The diagram indicates that the prevailing swell direction, shown by the largest spokes, was E, whereas the the prevailing wind blows from the NW. 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 26% of the time, equivalent to 8 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal July but 15% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 15%, equivalent to (5 days). Taking into account the ratio of these swells that coincided with predicted offshore winds, and given the fact that Ansteys is exposed to open water swells, we calculate that clean surf can be found at Ansteys about 26% of the time and that surf is messed up by onshore wind 25% of the time. This is means that we expect 16 days with waves in a typical July, of which 8 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.