This image shows only the swells directed at Bunbury Surf Club Backbeach that coincided with light winds or offshore conditions through a typical July. 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 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 the biggest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how frequently that size swell happens.
The diagram suggests that the prevailing swell direction, shown by the longest spokes, was SW, whereas the the prevailing wind blows from the W. 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 27% of the time, equivalent to 8 days. Open water swells exceeding >3m (>10ft) only arise 4% of the time in a typical July, equivalent to just one day but 15% of the time we expect swell in the range 2-3m (6.5-10ft) 15%, equivalent to (5 days). Taking into account the fraction of these swells that coincided with expected offshore winds, and given the fact that Bunbury Surf Club Backbeach is slightly protected from open water swells, we estimate that clean surf can be found at Bunbury Surf Club Backbeach about 27% of the time and that surf is blown out by onshore wind 65% of the time. This is means that we expect 29 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.