Local Winds

Wind is responsible for creating surf, but the wind in the last couple of miles at the beach also has a profound effect on the waves produced on the beach. When we talk about wind we talk about the direction which it comes from, for example a North wind blows from the North to the South. We also talk about wind as onshore, offshore and cross-shore.

Onshore

Onshore wind blows from the sea to the land. It pushes on the back of incoming waves. This extra pressure causes waves to break earlier and in deeper water, particularly on more gently sloping beaches this generally creates a less steep wave face than would otherwise be the case. Because the wind is unlikely to be blowing perfectly steadily and because the waves themselves influence the wind as it blows over the surface of the sea the effect of the wind isn’t uniform. Surfers would describe the conditions created as ‘messy’ and this is a pretty good description. The uneven effect of the wind causes waves to break early in places, these broken waves still running in deeper water then start to reform and break again. The overall effect is rarely to make for better surfing conditions. Generally the stronger the wind and the more directly it blows from sea to land the worse the situation.

Offshore

Offshore wind blows from the land to the sea and slows wave breaking. It holds the lip up and stops it spilling forward. On gently sloping beaches this means the wave will tend to break in shallower water and have more power when it does so and better shape. Likewise even on an shallow reef break this delay in the breaking point creates an even more powerful wave breaking more evenly along a shelf.

As the offshore wind gets stronger these benefits are enhanced, but as surfers the wave will tend to create a strong updraft from this wind. This can make it difficult to paddle into the breaking wave and make it more difficult to re-enter the wave after a turn.

The perfect wind does vary from beach to beach, but light offshores are most surfers choice. Once the wind reaches gust speeds of about 20mph some of the negative effects will start to be felt (although largely still preferable to onshore conditions).

Cross shore winds blow sideways along the beach, at light speeds they offer no huge issue but at stronger speeds cause some confusion in the surf. Of course in the real world the wind rarely blows directly on or directly offshore and these effects will vary on both the strength and angle of the wind.

The complete absence of wind leads to the ultimate ‘glassy’ conditions where the sea can look almost like oil on the surface and the waves break in a predictable manner great for surfing.

Shelter

The wind model also works on a grid, again it won’t take into effect local conditions, the shelter of a cliff or pier or the funnelling of the wind down a narrow valley. As with the swell forecast you will have a very good idea of the general conditions but need to use some local experience to fine tune the forecast.

Gusts

The gusting wind can blow to twice the steady strength. It’s important to use a forecast that gives both the average steady strength but also some idea of the gust you could expect. a 9mph onshore is probably worth a look if the swell is good. A 9mph gusting to 18mph wind will make for very confused and difficult conditions.

Convection

In many climates the sea temperature is different to the air and as importantly the sea will absorb heat from the sun more slowly than the land. Heat the land and the air will rise, creating low pressure, if the sea is colder air will move from the sea to the land making a local wind. These effects are so local (often only a mile or so from the coast) they are most normally missed by wind models but they are fairly easy to estimate. They tend to be at their worst in spring. When the sea is still cold from the winter but the first warm sunny days are heating the land. Typically in this situation you’ll get an offshore breeze in the morning (from the cold land overnight falling below sea temperature) building to a strong onshore breeze in the afternoon (as the land heats much faster than the sea) and calm conditions in early evening (as the land cools again). It’s unlikely that your wind forecast is taking this perfectly into account and you’ll need to be aware of it. As a very general rule of thumb expect the forecast to be under estimating the winds mid afternoon.

Fronts

Sometimes sitting in the line up you’ll see a band of dark cloud moving in from the ocean. This can mark the arrival of a storm front and you’ll often see a marked change in conditions as it passes. Rain can fall, the wind particularly can gust and even temperature can change by a few degrees – the passing of this boundary between different air masses can lead to a change in conditions for the better or worse but it’s normally worth hanging around long enough to see!