The graph describes how often and how strongly the wind blows from different directions through a typical June. The largest spokes point in the directions the wind most commonly blows from and the shade of blue implies the strength, with dark blue showing the strongest winds. It is based on 1593 NWW3 forecasts of wind since since 2006, at 3hr intervals, for the closest NWW3 model node to Bidart, located 34 km away (21 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 Bidart blows from the WNW. If the rose diagram shows a close to circular outline, it means there is no strong bias in wind direction at Bidart. On the other hand, 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 June, the model suggests that winds are light enough for the sea to be glassy (pale blue) about 25% of the time (8 days each June) and blows offshore 34% of the time (9 days in an average June). During a typical June wind stronger than >40kph (25mph) was expected for only a single days at Bidart
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.