Arinaga Swell Statistics, September: All Swell – Any Wind
The figure shows the range of swells directed at Arinaga through an average September and is based upon 2400 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 Arinaga. In the case of Arinaga, the best grid node is 42 km away (26 miles).
The rose diagram describes the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but lacks 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 illustrates biggest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the dominant swell direction, shown by the biggest spokes, was N, whereas the the prevailing wind blows from the NNE. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Arinaga and offshore. We lump these in with the no surf category of the bar chart. To avoid confusion we don't show these in the rose plot. Because wind determines whether or not waves are surfable at Arinaga, 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 September, swells large enough to cause good for surfing waves at Arinaga run for about 2.0% 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.