The rose diagram describes the variation of swells directed at Goolwa through an average May and is based upon 1488 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the coast so we have chosen the best grid node based on what we know about Goolwa. In the case of Goolwa, the best grid node is 26 km away (16 miles).
The rose diagram illustrates the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred only 1.4% of the time. Green and yellow illustrate increasing swell sizes and red shows the highest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the most common swell direction, shown by the largest spokes, was SSW, whereas the the dominant wind blows from the NW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Goolwa and away from the coast. We group these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose diagram. Because wind determines whether or not waves are surfable at Goolwa, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical May, swells large enough to cause good for surfing waves at Goolwa run for about 99% of the time.
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.