The rose diagram shows only the swells directed at Uatotoka that coincided with light winds or offshore conditions through a typical August. 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 illustrate increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. In both graphs, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the prevailing swell direction, shown by the longest spokes, was SSW, whereas the the most common wind blows from the ESE. 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 10% of the time, equivalent to 3 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal August but 6% of the time we expect swell in the range 2-3m (6.5-10ft) 6%, equivalent to (2 days). Taking into account the ratio of these swells that coincided with expected offshore winds, and given the fact that Uatotoka is exposed to open water swells, we estimate that clean surf can be found at Uatotoka about 10% of the time and that surf is blown out by onshore wind 73% of the time. This is means that we expect 26 days with waves in a typical August, of which 3 days should be clean enough to surf.
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.