This chart shows the combination of swells directed at Middleton Point through an average April and is based upon 1638 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the shore so we have chosen the optimum grid node based on what we know about Middleton Point. In this particular case the best grid node is 20 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 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 3% of the time. Green and yellow show increasing swell sizes and red shows biggest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how often that size swell occurs.
The diagram indicates that the dominant swell direction, shown by the longest spokes, was SSW, whereas the the prevailing wind blows from the SE. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Middleton Point and away from the coast. 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 surfable at Middleton Point, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical April, swells large enough to cause good for surfing waves at Middleton Point run for about 97% 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.