July 4, 2022

How to read a surf forecast

Stop pestering others with the question: “Where to skate tomorrow?” Instead, learn to choose for yourself

Sooner or later, any surfer gets tired of pestering more experienced friends with the question of where to ride tomorrow.

It becomes necessary to read the surf forecast yourself. Today I will tell you where and how to do it.

One of the most famous surf forecast sites globally is magicseaweed.com (from now on, I will briefly call it MSW); it has 102 countries and several thousand spots in its database

The world is divided into 12 regions; each region has a dozen countries/areas, each corresponding to a certain number of surf spots.

In Bali, for example, 29 spots are indicated; in Russia, 22 (yes, there are so many), there is even one spot in Antarctica! Naturally, there are more spots; it is just that the site lists the main ones known to everyone, but the locals in each region 100% know a lot of secret places; they do not mainly spread about them.

If suddenly there is no spot on the MSW website where you want to see the forecast, choose the closest one on the map.

Another big plus of the MSW site is the detailed description of each spot: the type of break, the bottom structure, and what conditions are required.

After you have found and selected the desired location, a page will open, where at first it is indicated what conditions are on it

Below is a short text and icons summarizing the conditions under which the spot works in principle.

Further, I will dwell on each indicator in detail, but for now, the general picture to understand where to look.

A forecast of conditions for ten days ahead is located below on the same page.

The surf forecast consists of four components:

  • The direction of the swell
  • The height of the waves
  • The strength and direction of the wind
  • The water level

Each of them defines different characteristics that ultimately give conditions on the spot.

If you pay attention to the column labels, you will notice a PRIMARY SWELL and a SECONDARY SWELL

The fact is that swells of different strengths are constantly moving towards the coast, catching up with each other and overlapping.

Roughly speaking, the remnants of today’s bubble become a secondary swell tomorrow. Its influence is not strong, so that it can be neglected in general.

Below we will consider only the primary wave.

Swell direction

Determines if the spot will work

The direction of the swell is responsible for the operation of the spot, that is, at what angle the waves come to the shore.

Some areas are susceptible to this indicator, for example, those in the bay: if the direction is wrong, the waves will not reach them.

Or the shape of the bottom is such that if the swell goes conventionally to the right, the locks will be long, even good, and if you get short flaps to the left.

However, most spots are not sensitive to slight variations, and many generally work in all swell directions.

Memorizing the appropriate swell direction for each spot is difficult, but it is unnecessary; the MSW website is all for people

The fourth icon in the description of the site shows the spectrum visually, and when you hover it with the mouse, a window pops up, where it is written which directions are suitable.

In the forecast, the direction of the swell is indicated by an arrow. Still, when you hover the mouse, more accurate data also pop up, which can already be easily compared with the information from the description of the spot.

If the direction is good and the spot works in principle, it’s time to determine what kind of waves there will be and whether you can ride there

Wave height

Determines the size and strength of waves

Two factors influence the wave height – the swell size and the period; therefore, two values ​​in the forecast correspond to it at once

The height of the swell is measured in meters; the larger it is, the more influential the waves come (logical), but the actual size of the waves depends very much on the period. The period is between two waves of the same set, measured in seconds.

The larger it is, the greater the wave height will be at the same swell height; in practice, the period is the coefficient with which the swell size and the resulting wave height are related.

To roughly understand what wave height awaits you on this forecast, remember this rule: with a period of 12-13 seconds, the wave height is related to the swell height as 1: 1.

If the size of the swell is 1.7 meters, and the period is 12 seconds, most likely, there will be waves of growth or slightly more development.

If the period is more than 14, the resulting wave will be above the swell; you can safely double it in 20-22 seconds.

Conversely, if the period is short, say 10 seconds, the wave height will be less than the swell height

Periods less than 10 seconds correspond to wind swells. On a short period, but with wind, the wave size can be larger than the swell size; such a picture is typical for the sea-coast during a storm.

So, for example, a forecast of 1 meter for 10 seconds for Sochi means sound waves with more growth, and in Bali, there will be days without surfing.

The description of the spot indicates which swell it works, and you can ride: if the swell is less, then the waves may not close or push, and if more, then, on the contrary, collapse along the entire length.

The size you are comfortable riding on a given spot can only be judged by experience.

The site is American, so the icons’ numbers are in feet

In the forecast settings, the units of measurement can be changed to meters, as I did, but the icon will remain the same, so you have to translate in your head.

Feet must be divided by 3 to get an approximate figure in meters. In this example, it turns out that the spot works on a swell from 1.3 to 4 meters.


Determines the quality of the wave

Whether the riding conditions are good or bad depends not only on the waves coming from the ocean but also on how the shore meets them

Even the smoothest and highest quality swell can turn into an unstable mess if a strong wind blows. If the wind blows from the coast, it is called off-shore and can even improve conditions by supporting and smoothing the wave wall.

If the wind blows on the beach, it is called onshore; this wind spoils the waves. Also, the tide begins to crumble ahead of time because of the onshore.

Finally, if the wind blows parallel to the beach or at a slight angle, it is called cross-shore, and here you have to look at the situation.

The direction of the wind, which does not spoil the conditions on the spot, is also indicated in the description, and as for its strength – the less, the better.

Overall MSW score

One may fear that artificial intelligence will enslave the world in the future, but its algorithms are working well to help humans so far.

So, MSW, analyzing its database, exposes an estimated wave height and an overall assessment of the quality of conditions.

Of course, this forecast is not always justified, but there are flaws on all sites

As for the asterisks, since MSW focuses on an excellent skating public, five stars represent big, even waves.

At the same time, for beginners, conditions of two or three stars may be better.

Therefore, the number of stars is formed as follows: first, all parameters are taken into account, except for the wind, and then, depending on the strength and direction of the wind, some of them are made translucent, thus showing how much the wind spoils the picture.

An English acquaintance of mine claimed that on spots where there are Magicseaweed partner stores, an asterisk is added to the forecast to attract more people, but the information is not verified.


Determine the best time of day to ride

Surf spots are mostly quite sensitive to changes in water level. And if some work at any tide, give waves of slightly different quality, others can turn off entirely on inappropriate water.

Again, the spot description indicates which water level is best for that spot

There is no need to predict the tides; they are determined by the moon and sun and calculated for many years.

Therefore, in the forecast, the daily change in water level is indicated below, we look at what time there will be suitable water, and we go

Sometimes, however, it is helpful to try a spot at different tide levels to determine how the wave behaves, depending on whether the water is decreasing or arriving.

Usually, waning water waves are sharper than wading water; also, depending on this factor, currents in the spot can be turned on or off.

In Bali, I tend to use surf-forecast.com instead of Magicseaweed

Since I am very familiar with how spots work, plus they are not very dependent on the direction of the swell here, I need to look at one figure, the energy of the tide, to understand what size the waves will be.

Power is specified in kilojoules and essentially aggregates the swell height and period.

The more energy, the larger and more powerful the waves will be. At the same time, each separately taken spot works well at a specific energy spectrum.

There are spot magnets where there are excellent waves of 300-400 kJ, while on others, there will be no waves at all in such an alignment. The 1500-2000 kJ energy usually corresponds to large, serious waves.

This single figure is unlikely to help on a new spot, so the MSW application on the phone in unfamiliar lands saves.

And, of course, you need to use your eyes, no matter what the forecast writes, you should observe the conditions from the shore, and then decide whether to go for a drive or not.

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