The figure illustrates how commonly and how strongly the wind blows from different directions through a typical southern hemisphere autumn. The longest spokes point in the directions the wind most commonly blows from and the shade of blue implies the strength, with the strongest winds shown by dark blue. It is based on 4858 NWW3 forecasts of wind since since 2007, at 3hr intervals, for the closest NWW3 model node to Rivoli Bay, located 4 km away (2 miles). There are not enough recording stations world wide to use actual wind data. No doubt some coastal places have very localized wind effects that would not be predicted by NWW3.
According to the model, the prevailing wind at Rivoli Bay blows from the SW. If the rose plot shows a nearly round shape, it means there is no strong bias in wind direction at Rivoli Bay. On the other hand, dominant spokes illustrate favoured directions, and the more deep blue, the stronger the wind. Spokes point in the direction the wind blows from. Over an average southern hemisphere autumn, the model suggests that winds are light enough for the sea to be glassy (the lightest shade of blue) about 14% of the time (13 days each southern hemisphere autumn) and blows offshore 37% of the time (33 days in an average southern hemisphere autumn). In a typical southern hemisphere autumn winds stronger than >40kph (25mph) are expected on 4 days at Rivoli Bay
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.