This picture shows how often and how strongly the wind blows from different directions through a typical northern hemisphere winter. The longest spokes point in the directions the wind most commonly blows from and the shade of blue implies the strength, with dark blue strongest. It is based on 5047 NWW3 forecasts of wind since since 2006, at 3hr intervals, for the closest NWW3 model node to Nahant Beach, located 35 km away (22 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 most common wind at Nahant Beach blows from the ENE. If the rose plot shows a nearly round shape, it means there is no strong bias in wind direction at Nahant Beach. By contrast, dominant spokes represent favoured directions, and the more the darkest shade of blue, the stronger the wind. Spokes point in the direction the wind blows from. Over an average northern hemisphere winter, the model suggests that winds are light enough for the sea to be glassy (the lightest shade of blue) about 4% of the time (4 days each northern hemisphere winter) and blows offshore just 23% of the time (15 days in an average northern hemisphere winter). In a typical northern hemisphere winter winds stronger than >40kph (25mph) are expected on 6 days at Nahant Beach
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.