The graph illustrates the variation of swells directed at Bob Hall Pier over a normal July, based on 1736 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the most applicable grid node based on what we know about Bob Hall Pier. In this particular case the best grid node is 24 km away (15 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 show increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. In each graph, 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 biggest spokes, was SE, whereas the the most common wind blows from the SSE. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Bob Hall Pier and away from the coast. We lump these in 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 Bob Hall Pier, you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. During a typical July, swells large enough to cause good for surfing waves at Bob Hall Pier run for about 92% 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.