Woonona Swell Statistics, Winter: All Swell – Any Wind
This image shows the range of swells directed at Woonona through a typical southern hemisphere winter and is based upon 5802 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 optimum grid node based on what we know about Woonona, and at Woonona the best grid node is 11 km away (7 miles).
The rose diagram describes the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These happened only 73% of the time. Green and yellow illustrate increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In either graph, the area of any colour is proportional to how often that size swell happens.
The diagram indicates that the dominant swell direction, shown by the largest spokes, was ENE, whereas the the prevailing wind blows from the W. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Woonona and offshore. We combine these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose plot. Because wind determines whether or not waves are good for surfing at Woonona, 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 clean enough to surf waves at Woonona run for about 27% 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.