This picture describes the combination of swells directed at Samoa Peninsula over a normal February and is based upon 1584 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the coast so we have chosen the most applicable grid node based on what we know about Samoa Peninsula. In the case of Samoa Peninsula, the best grid node is 33 km away (21 miles).
The rose diagram illustrates the distribution of swell sizes and directions, 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 occurred only 8% of the time. Green and yellow represent increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In both graphs, the area of any colour is proportional to how frequently that size swell happens.
The diagram suggests that the prevailing swell direction, shown by the biggest spokes, was WNW, whereas the the dominant wind blows from the W. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Samoa Peninsula 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 good for surfing at Samoa Peninsula, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical February, swells large enough to cause clean enough to surf waves at Samoa Peninsula 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.