Castles Swell Statistics, August: All Swell – Any Wind
This image illustrates the variation of swells directed at Castles through a typical August. It is based on 1984 NWW3 model predictions since 2006 (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 Castles. In the case of Castles, the best grid node is 32 km away (20 miles).
The rose diagram shows the distribution of swell directions and swell sizes, 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 17% of the time. Green and yellow represent increasing swell sizes and red represents the largest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the most common swell direction, shown by the longest spokes, was SE, whereas the the most common 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 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 Castles, you can load a different image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. Over an average August, swells large enough to cause surfable waves at Castles run for about 83% 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.