The figure shows the variation of swells directed at Playa de Aizkorri through a typical April. It is based on 1646 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the most applicable grid node based on what we know about Playa de Aizkorri, and at Playa de Aizkorri the best grid node is 13 km away (8 miles).
The rose diagram describes 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 occurred only 8% of the time. Green and yellow represent increasing swell sizes and red represents the biggest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell occurs.
The diagram implies that the dominant swell direction, shown by the biggest spokes, was NW (which was the same as the prevailing wind direction). Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Playa de Aizkorri 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 Playa de Aizkorri, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average April, swells large enough to cause surfable waves at Playa de Aizkorri run for about 92% 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.