This chart describes how often and how strongly the wind blows from different directions over a normal northern hemisphere autumn. The largest spokes point in the directions the wind most commonly blows from and the shade of blue suggests the strength, with the strongest winds shown by the darkest shade of blue. It is based on 5144 NWW3 forecasts of wind since since 2006, at 3hr intervals, for the closest NWW3 model node to Portreath Beach, located 30 km away (19 miles). There are too few recording stations world wide to use actual wind data. Invevitably some coastal places have very localized wind effects that would not be predicted by NWW3.
According to the model, the most common wind at Portreath Beach 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 Portreath 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. During a typical northern hemisphere autumn, the model suggests that winds are light enough for the sea to be glassy (pale blue) about 4% of the time (4 days each northern hemisphere autumn) and blows offshore just 20% of the time (11 days in an average northern hemisphere autumn). Over an average northern hemisphere autumn winds stronger than >40kph (25mph) are expected on 14 days at Portreath 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.