This chart describes how frequently and how strongly the wind blows from different directions over a normal March. The longest spokes point in the directions the wind most commonly blows from and the shade of blue indicates the strength, with dark blue showing the strongest winds. It is based on 1724 NWW3 forecasts of wind since since 2007, at 3hr intervals, for the closest NWW3 model node to La Tranche sur Mer, located 44 km away (27 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 La Tranche sur Mer blows from the W. If the rose graph shows a fairly circular pattern, it means there is no strong bias in wind direction at La Tranche sur Mer. By contrast, dominant spokes show favoured directions, and the more deep blue, the stronger the wind. Spokes point in the direction the wind blows from. During a typical March, the model suggests that winds are light enough for the sea to be glassy (the lightest shade of blue) about 7% of the time (2 days each March) and blows offshore 37% of the time (11 days in an average March). Over an average March winds stronger than >40kph (25mph) are expected on 3 days at La Tranche sur Mer
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.