Needles Swell Statistics, Spring: All Swell – Any Wind
This image shows the variation of swells directed at Needles through a typical northern hemisphere spring. It is based on 5140 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 Needles. In the case of Needles, the best grid node is 13 km away (8 miles).
The rose diagram illustrates the distribution of swell sizes and swell direction, 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 happened only 1.7% 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 WSW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Needles and out to sea. We combine these with the no surf category of the bar chart. To simplify things we don't show these in the rose diagram. Because wind determines whether or not waves are surfable at Needles, you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. Over an average northern hemisphere spring, swells large enough to cause good for surfing waves at Needles run for about 98% 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.