Reading one of our wave forecasts it's as easy as any other chart.
The vertical axis represents wave height, and the horizontal one represents hour and day (today, tomorrow, next day).
You only have to consider which moment you are interesed into, and move along the chart consequently.
So, 1st day at noon, the swell will be 1.2 metres coming from the northwest. Your shoreline knowledge will help you to decide which spot works the best with the predicted swell.
You will find a similar chart for the wind, but without vertical axis.
Wind speed is given by the square's colour: as it gets darker, the wind is weaker. These colour changes will give you an approximation of how the wind changes along the days.
Furthermore, you can see wind speed measured in km/h and its direction. As a general rule, any onshore wind faster than 20 km/h is quite annoying, so it would be better if the chart colours are the less bluish as possible.
In the global communications era, we can access a lot of prediction websites that show us the present swell conditions. Most of them are based upon different models and hence, they offer different results.
However, don't be fooled by the accuracy they seem to show. In weather science there's a truth: as time
passes by, the forecast becomes less reliable. After 4 days, a certain weather forecast has only half the chances
of being true. This becomes even truer when there are more variables involved.
And there are a bunch of variables if you consider air pressure, the wind and the sea surface.
In the long term, such prediction becomes less accurate and reliable; and we would be talking more about Climatology than Meteorology. Everybody is able to predict that will rain this coming fall and there will be some swells, right?. The key point is the short term certainty.
A forecast close to reality is preferred over another one with a lot of decimals, every minute, but completely inaccurate.
And keep in mind that the waves; the swell, it's generated by the wind. Wind produces surface waves, and fetching these little ripples along a large distance becomes the "swell" that arrives to the shoreline.
Here at olas.info we use the Agencia Estatal de Meteorología's swell model to make our charts. AEMET operates some computer programs known as HIRLAM and WAME that produce very precise predictions. These data is compared to real buoy measures, so they can tune the models and improve the upcoming predictions. Therefore, the buoys located in open sea don't produce predictions, they simply retrieve data to help improve the models.
So now… would you trust in any other forecast source?