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Grandma's ratings
Quality on a good day: 1.0
Consistency of Surf: 3.0
Difficulty Level: 1.0
Crowds: 2.0

Overall: 2.4

See all 18 ratings

Based on 2 votes. Vote


Surf Report Feed

Grandma's Swell Statistics, Summer: All Swell – Any Wind

The rose diagram describes the range of swells directed at Grandma's through an average northern hemisphere summer and is based upon 8738 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the best grid node based on what we know about Grandma's. In the case of Grandma's, the best grid node is 33 km away (21 miles).

The rose diagram shows the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These occurred only 42% of the time. Green and yellow illustrate increasing swell sizes and red shows the highest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how commonly that size swell was forecast.

The diagram implies that the dominant swell direction, shown by the biggest spokes, was SSW, whereas the the dominant wind blows from the ENE. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Grandma's and out to sea. We lump these in with the no surf category of the bar chart. To keep it simple we don't show these in the rose diagram. Because wind determines whether or not waves are good for surfing at Grandma's, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical northern hemisphere summer, swells large enough to cause clean enough to surf waves at Grandma's run for about 58% 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.