Box Beach Swell Statistics, April: All Swell – Any Wind
The figure illustrates the combination of swells directed at Box Beach through a typical April, based on 2160 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the best grid node based on what we know about Box Beach. In the case of Box Beach, the best grid node is 34 km away (21 miles).
The rose diagram shows the distribution of swell sizes and directions, 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 were forecast only 10% of the time. Green and yellow show increasing swell sizes and red illustrates the largest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the dominant swell direction, shown by the longest spokes, was SE, whereas the the most common wind blows from the S. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Box Beach 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 graph. Because wind determines whether or not waves are surfable at Box Beach, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. Over an average April, swells large enough to cause good for surfing waves at Box Beach run for about 90% 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.