St Ives Harbour Wall Surf Stats

This picture shows the range of swells directed at St Ives Harbour Wall through a typical October, based on 3471 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 directions and swell sizes, while the graph at the bottom shows the same thing without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These were forecast only 15% of the time. Green and yellow show increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In each graph, the area of any colour is proportional to how frequently that size swell occurs. The diagram suggests that the most common swell direction, shown by the longest spokes, was W, whereas the the prevailing wind blows from the SW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from St Ives Harbour Wall and offshore. We combine these 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 surfable at St Ives Harbour Wall, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. Over an average October, swells large enough to cause good for surfing waves at St Ives Harbour Wall run for about 33% of the time.

read more