Aberdaron Swell Statistics, December: All Swell – Any Wind
This chart describes the combination of swells directed at Aberdaron through an average December and is based upon 2457 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the most applicable grid node based on what we know about Aberdaron, and at Aberdaron the best grid node is 36 km away (22 miles).
The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but without direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These happened only 32% of the time. Green and yellow show increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. 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 WSW, whereas the the dominant wind blows from the SW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Aberdaron 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 plot. Because wind determines whether or not waves are clean enough to surf at Aberdaron, you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical December, swells large enough to cause surfable waves at Aberdaron run for about 49% 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.