Napier - Marine Parade Swell Statistics, September: All Swell – Any Wind
This picture shows the range of swells directed at Napier - Marine Parade over a normal September. It is based on 2294 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 best grid node based on what we know about Napier - Marine Parade. In the case of Napier - Marine Parade, the best grid node is 7 km away (4 miles).
The rose diagram illustrates the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but 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 78% of the time. Green and yellow represent increasing swell sizes and red represents the biggest swells, greater than >3m (>10ft). In either graph, 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 longest spokes, was ENE, whereas the the prevailing wind blows from the NW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Napier - Marine Parade 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 graph. Because wind determines whether or not waves are good for surfing at Napier - Marine Parade, 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 September, swells large enough to cause clean enough to surf waves at Napier - Marine Parade run for about 22% 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.