St Ives Harbour Wall Surf Stats

This image shows the combination of swells directed at St Ives Harbour Wall through an average July. It is based on 3472 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the coastline so we have chosen the best grid node based on what we know about St Ives Harbour Wall. In this particular case the best grid node is 32 km away (20 miles). The rose diagram illustrates the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred only 7% of the time. Green and yellow show increasing swell sizes and red shows biggest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how often that size swell happens. The diagram indicates that the dominant swell direction, shown by the largest spokes, was W (which was the same as the prevailing wind direction). Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from St Ives Harbour Wall and out to sea. We lump these in 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 St Ives Harbour Wall, 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 July, swells large enough to cause surfable waves at St Ives Harbour Wall run for about 18% of the time.

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