Castles Swell Statistics, August: All Swell – Any Wind
The figure describes the combination of swells directed at Castles over a normal August, based on 2232 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the most applicable grid node based on what we know about Castles. In this particular case the best grid node is 32 km away (20 miles).
The rose diagram describes the distribution of swell sizes and directions, while the graph at the bottom shows the same thing without direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These occurred only 16% of the time. Green and yellow show increasing swell sizes and red shows highest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the most common swell direction, shown by the biggest spokes, was SE, whereas the the dominant wind blows from the SW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Castles and offshore. We group 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 Castles, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical August, swells large enough to cause clean enough to surf waves at Castles run for about 84% 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.