The figure shows how frequently and how strongly the wind blows from different directions through a typical northern hemisphere summer. The biggest 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 5066 NWW3 forecasts of wind since since 2006, at 3hr intervals, for the closest NWW3 model node to Penhors, located 9 km away (6 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 prevailing wind at Penhors blows from the W. If the rose plot shows a nearly round shape, it means there is no strong bias in wind direction at Penhors. By contrast, dominant spokes illustrate favoured directions, and the more dark blue, the stronger the wind. Spokes point in the direction the wind blows from. Over an average northern hemisphere summer, the model suggests that winds are light enough for the sea to be glassy (pale blue) about 9% of the time (8 days each northern hemisphere summer) and blows offshore 17% of the time (15 days in an average northern hemisphere summer). In a typical northern hemisphere summer winds stronger than >40kph (25mph) are expected on 2 days at Penhors
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.