This image shows only the swells directed at Jacobs Bay that coincided with light winds or offshore conditions over a normal June. It is based on 1600 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 illustrate 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 often that size swell occurs.
The diagram indicates that the prevailing swell direction, shown by the biggest spokes, was SW (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 35% of the time, equivalent to 10 days. Expect open water swells to exceed >3m (>10ft) 7% of the time (2 days). Taking into account the ratio of these swells that coincided with predicted offshore winds, and given the fact that Jacobs Bay is exposed to open water swells, we estimate that clean surf can be found at Jacobs Bay about 35% of the time and that surf is blown out by onshore wind 61% of the time. This is means that we expect 29 days with waves in a typical June, of which 10 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.