This picture describes the range of swells directed at Red Bluff through a typical December, based on 1736 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the coast so we have chosen the most applicable grid node based on what we know about Red Bluff. In this particular case the best grid node is 16 km away (10 miles).
The rose diagram illustrates the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These occurred only 46% of the time. Green and yellow show increasing swell sizes and red illustrates highest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the most common swell direction, shown by the longest spokes, was SE, whereas the the dominant wind blows from the SSE. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Red Bluff and offshore. We lump these in with the no surf category of the bar chart. To avoid confusion we don't show these in the rose graph. Because wind determines whether or not waves are good for surfing at Red Bluff, you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. Over an average December, swells large enough to cause clean enough to surf waves at Red Bluff run for about 54% of the time.
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.