The rose diagram describes how often and how strongly the wind blows from different directions over a normal October. The largest 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 the darkest shade of blue. It is based on 1736 NWW3 forecasts of wind since since 2006, at 3hr intervals, for the closest NWW3 model node to Barra da Cuanza, located 23 km away (14 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 dominant wind at Barra da Cuanza blows from the SW. If the rose plot shows a nearly round shape, it means there is no strong bias in wind direction at Barra da Cuanza. By contrast, dominant spokes represent favoured directions, and the more the darkest shade of blue, the stronger the wind. Spokes point in the direction the wind blows from. During a typical October, the model suggests that winds are light enough for the sea to be glassy (light blue) about 18% of the time (6 days each October) and blows offshore 19% of the time (6 days in an average October). Over an average October winds exceeding >40kph (25mph) are not expected, but 0 have winds on the range 30-40 (19-25) at Barra da Cuanza
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.