The figure illustrates 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 implies the strength, with deep blue strongest. It is based on 1736 NWW3 forecasts of wind since since 2006, at 3hr intervals, for the closest NWW3 model node to Porto da Cruz, located 31 km away (19 miles). There are too few 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 most common wind at Porto da Cruz blows from the N. If the rose diagram shows a close to circular outline, it means there is no strong bias in wind direction at Porto da Cruz. Converseley, 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 (light blue) about 5% of the time (2 days each August) and blows offshore 6% of the time (1 days in an average August). During a typical August winds exceeding >40kph (25mph) are not expected, but 6 have winds on the range 30-40 (19-25) at Porto da Cruz
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.