Mount Maunganui Swell Statistics, January: All Swell – Any Wind
The figure shows the variation of swells directed at Mount Maunganui through an average January. It is based on 2124 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the shore so we have chosen the best grid node based on what we know about Mount Maunganui, and at Mount Maunganui the best grid node is 32 km away (20 miles).
The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing without direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These were forecast only 17% of the time. Green and yellow illustrate increasing swell sizes and biggest swells greater than >3m (>10ft) are shown in red. In either 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 biggest spokes, was NE, whereas the the prevailing wind blows from the NW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Mount Maunganui and offshore. We combine these 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 surfable at Mount Maunganui, you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical January, swells large enough to cause good for surfing waves at Mount Maunganui run for about 23% 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.