The rose diagram shows how often and how strongly the wind blows from different directions through a typical August. The biggest spokes point in the directions the wind most commonly blows from and the shade of blue suggests the strength, with deep blue showing the strongest winds. It is based on 1736 NWW3 forecasts of wind since since 2006, at 3hr intervals, for the closest NWW3 model node to Nosy Andrea, located 25 km away (16 miles). There are not enough recording stations world wide to use actual wind data. Without question some coastal places have very localized wind effects that would not be predicted by NWW3.
According to the model, the most common wind at Nosy Andrea blows from the SSW. If the rose graph shows a fairly circular pattern, it means there is no strong bias in wind direction at Nosy Andrea. By contrast, dominant spokes show favoured directions, and the more dark blue, the stronger the wind. Spokes point in the direction the wind blows from. Over an average August, the model suggests that winds are light enough for the sea to be glassy (pale blue) about 14% of the time (4 days each August) and blows offshore 36% of the time (1 days in an average August). In a typical August wind stronger than >40kph (25mph) was predicted for only a single days at Nosy Andrea
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.