The graph illustrates the combination of swells directed at Newcastle - The Wedge 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 coastline so we have chosen the best grid node based on what we know about Newcastle - The Wedge. In this particular case the best grid node is 21 km away (13 miles).
The rose diagram describes the distribution of swell directions and swell sizes, 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 were forecast only 54% of the time. Green and yellow show increasing swell sizes and red shows largest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the dominant swell direction, shown by the longest spokes, was E, whereas the the most common wind blows from the WSW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Newcastle - The Wedge and away from the coast. We combine 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 surfable at Newcastle - The Wedge, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical May, swells large enough to cause good for surfing waves at Newcastle - The Wedge run for about 46% 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.