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I and Js ratings
Quality on a good day: 2.0
Consistency of Surf: 3.0
Difficulty Level: 3.0
Crowds: 4.0

Overall: 3.0

See all 18 ratings

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Surf Report Feed

I and Js Swell Statistics, July: All Swell – Any Wind

This picture describes the range of swells directed at I and Js over a normal July. It is based on 2976 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the shore so we have chosen the most applicable grid node based on what we know about I and Js. In this particular case the best grid node is 35 km away (22 miles).

The rose diagram illustrates the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These happened only 13% of the time. Green and yellow show increasing swell sizes and red illustrates highest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how frequently that size swell happens.

The diagram suggests that the dominant swell direction, shown by the longest spokes, was SW (which was the same as the dominant wind direction). Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from I and Js and offshore. We combine these with the no surf category of the bar chart. To simplify things we don't show these in the rose graph. Because wind determines whether or not waves are surfable at I and Js, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. During a typical July, swells large enough to cause good for surfing waves at I and Js run for about 87% 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.

FEATURE UPDATE: we now show red swell icons for 'open sea' swells that are travelling in an unfavourable direction for the surf break. In places, these swells may still wrap around coastlines and produce smaller waves at some breaks. They are also significant for windsurfers and other water users that tend to venture further off-shore.