Windy Harbour Swell Statistics, Summer: All Swell – Any Wind
This picture describes the variation of swells directed at Windy Harbour over a normal southern hemisphere summer, based on 6365 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the shore so we have chosen the optimum grid node based on what we know about Windy Harbour. In the case of Windy Harbour, the best grid node is 19 km away (12 miles).
The rose diagram describes 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 happened only 1.0% of the time. Green and yellow show increasing swell sizes and red illustrates the highest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell happens.
The diagram indicates that the most common swell direction, shown by the longest spokes, was SW, whereas the the dominant wind blows from the SSE. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Windy Harbour and out to sea. We group these with the no surf category of the bar chart. To keep it simple we don't show these in the rose diagram. Because wind determines whether or not waves are clean enough to surf at Windy Harbour, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. During a typical southern hemisphere summer, swells large enough to cause surfable waves at Windy Harbour 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.