The rose diagram illustrates the variation of swells directed at Playa de Niembro through an average August and is based upon 1736 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the best grid node based on what we know about Playa de Niembro. In the case of Playa de Niembro, the best grid node is 21 km away (13 miles).
The rose diagram illustrates the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but 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 23% of the time. Green and yellow represent increasing swell sizes and red represents largest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how often that size swell was forecast.
The diagram indicates that the dominant swell direction, shown by the largest spokes, was NW, whereas the the most common wind blows from the N. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Playa de Niembro and out to sea. We combine these with the no surf category of the bar chart. To simplify things we don't show these in the rose plot. Because wind determines whether or not waves are clean enough to surf at Playa de Niembro, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical August, swells large enough to cause surfable waves at Playa de Niembro run for about 5% 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.