Ko Samui Surf Stats

This chart describes the range of swells directed at Ko Samui over a normal May. It is based on 3439 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the coast so we have chosen the best grid node based on what we know about Ko Samui. In the case of Ko Samui, the best grid node is 49 km away (30 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 were forecast 96% of the time. Green and yellow show increasing swell sizes and red illustrates highest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how often that size swell happens. The diagram indicates that the prevailing swell direction, shown by the largest spokes, was SE, whereas the the dominant wind blows from the SSW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Ko Samui 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 good for surfing at Ko Samui, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. During a typical May, swells large enough to cause clean enough to surf waves at Ko Samui run for about 4% of the time.

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