This chart illustrates the combination of swells directed at Trial Harbour through an average southern hemisphere autumn, based on 4858 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the coast so we have chosen the most applicable grid node based on what we know about Trial Harbour, and at Trial Harbour the best grid node is 16 km away (10 miles).

The rose diagram shows 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 happened only 0.3% of the time. Green and yellow illustrate increasing swell sizes and red illustrates the largest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how frequently that size swell was forecast.

The diagram suggests that the most common swell direction, shown by the largest spokes, was SW, whereas the the most common wind blows from the WNW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Trial Harbour and away from the coast. 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 clean enough to surf at Trial Harbour, you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical southern hemisphere autumn, swells large enough to cause surfable waves at Trial Harbour run for about 100% 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.