Despretes Swell Statistics, Summer: All Swell – Any Wind
The graph describes the range of swells directed at Despretes through an average southern hemisphere summer. It is based on 6365 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 most applicable grid node based on what we know about Despretes. In this particular case the best grid node is 23 km away (14 miles).
The rose diagram describes the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but lacks direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These occurred 61% of the time. Green and yellow illustrate increasing swell sizes and red represents the highest 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 most common swell direction, shown by the biggest spokes, was SSW, whereas the the dominant wind blows from the NNW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Despretes 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 plot. Because wind determines whether or not waves are surfable at Despretes, you can load a different image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical southern hemisphere summer, swells large enough to cause good for surfing waves at Despretes run for about 39% 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.