This picture describes how frequently and how strongly the wind blows from different directions over a normal December. The largest spokes point in the directions the wind most commonly blows from and the shade of blue implies the strength, with the strongest winds shown by the darkest shade of blue. It is based on 1240 NWW3 forecasts of wind since since 2008, at 3hr intervals, for the closest NWW3 model node to Ventnor, located 17 km away (11 miles). There are insufficient 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 Ventnor blows from the SW. If the rose graph shows a fairly circular pattern, it means there is no strong bias in wind direction at Ventnor. By contrast, dominant spokes represent favoured directions, and the more dark blue, the stronger the wind. Spokes point in the direction the wind blows from. During a typical December, the model suggests that winds are light enough for the sea to be glassy (light blue) about 2% of the time (1 days each December) and blows offshore just 14% of the time (2 days in an average December). Over an average December winds stronger than >40kph (25mph) are expected on 6 days at Ventnor
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.