The graph shows the combination of swells directed at Lauderdale Point through a typical southern hemisphere winter. It is based on 5072 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coast so we have chosen the best grid node based on what we know about Lauderdale Point. In this particular case the best grid node is 65 km away (40 miles).
The rose diagram illustrates the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but lacks direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred only 8% of the time. Green and yellow represent increasing swell sizes and red shows biggest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell occurs.
The diagram implies that the most common swell direction, shown by the biggest spokes, was SW, whereas the the prevailing wind blows from the WNW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Lauderdale Point and out to sea. We group these with the no surf category of the bar chart. To simplify things we don't show these in the rose plot. Because wind determines whether or not waves are clean enough to surf at Lauderdale Point, you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. Over an average southern hemisphere winter, swells large enough to cause surfable waves at Lauderdale Point run for about 25% 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.