Sao Marcos
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Hourly Forecast
Timezone: America/Fortaleza
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⚡️kJ
Saturday 13
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Sao Marcos surf guide

Sao Marcos is a surf spot that might not be the best option for everyone. It's located near a river mouth and has some unique features that you should know about. The area attracts a mix of surfers, but don’t expect to find epic waves here too often. The surroundings can be a bit busy with tankers coming through, so keep that in mind when planning your session.

The surf at Sao Marcos works best with a NorthEast swell, but it can also pick up waves from the North and East. It handles swell sizes around 2ft (about 0.6 meters) well, breaking over sandy bottoms. You’ll find both left and right waves here, which can be fun, especially for beginners. The best conditions usually come with a South wind, and it’s recommended to surf during mid to high tides.

If you’re looking for variety, Ponta da Areia is just around the point to the west. It’s deeper in the river mouth and might have better days, although it doesn’t break that often. Expect more surfers to show up there when the waves are decent. If you decide to stick to Sao Marcos, it can be a nice chill spot for beginner surfers to practice without too much competition.

Surf reports and surf forecasts nearby Sao Marcos

Crispim
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Beach break
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Vila do Algodoal
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Beach break
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Atalaia
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Beach break
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Marieta - Para
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Beach break
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Praia De Ajuruteua
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Beach break
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Rio Capim
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Rivermouth break
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Itatinga
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Beach break
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Sao Marcos
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Beach break
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Araçagi
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Beach break
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Rio Mearim
Unknown Region, Unknown Country
Rivermouth break
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Wind certainty

Wind certainty tells you how much the weather models agree on the forecast.

  • High certainty: Models agree closely; forecast is reliable.
  • Medium certainty: Some disagreement; conditions may shift slightly.
  • Low certainty: Models diverge; treat forecast with caution.

We calculate this by comparing wind speed, gust and direction from multiple models (like GFS, ECMWF, Arome, and Harmonie) and seeing how closely they match. They are weighted, meaning that some models count more than others, depending on how good they are for a certain spot.

Readme

Welcome! If you’re new to surf forecasting, check out this quick guide.

Forecast Table

The forecast table (the section on the page with all the numbers) is designed to pack as much information in the screen as possible. Although intimidating at first, it will help you make informed decisions about the waves faster, trust me :D. The table consists of roughly four sections, time and predictions, wind, waves, and tides:

🔮 Time and predictions section

Here we show the forecast thour and the overall surf quality prediction. This is determined based on the wave, wind and tide quality prediction. These individual predictions can be found on the forecast map.

💨 Wind section

The first row on the table (with the 💨 icon) shows wind speed, direction and gust. The more the wind speed the more aggressive the color (from blue, green, orange to red).

🌊 Wave section

The waves section consists of three rows, one for wave height and direction, one for period and one for wave energy. Our algorithm choices the "dominant wave". This is normally the first swell partition, but with heavy local storms it displays the wind waves. If that's the case, we display the numbers in italic and in gray.

🌒 Tide section

The tide section consists of a row with the actual heights per hour (measured at the half hour) and a table that displays the flow of the tide and the extremes (lows and highs).

Forecast map

The forecast map consists of arrows. These arrows represent all wave partitions (swell partitions and wind wave partition) and the wind. This allows you to see things like: a secondary swell or wind waves messes up the surf, or the wind is just a tick offshore so very surfable. Click a metric label in the bottom left to bring that arrow to the front — handy when arrows overlap.

Forecast Cheat Sheet

Short on time? Focus on wave energy. It’s the best single metric to gauge how big and powerful the waves will be.

Click any table cell to jump to that forecast hour. The map will update with forecast arrows, so you can see if wind and swell direction are lining up.

Use the table sidebar to switch units for height and speed.

Log your surf sessions to compare forecasts with real sessions and sharpen future predictions.

Models and Updates

Surfnerd blends multiple global and local wind and swell models using advanced interpolation and spatial techniques to create an "ensemble" forecast. Forecasts are refreshed hourly.

Surf Predictions

Our AI-driven algorithm scores surf quality, shown by green, orange, and gray dots. Each forecast hour is rated for wind, swell, and tide quality, then combined into an overall score. Here’s the scale:

Perfect
Good
Average
Bad or No Data

Session logs also feed the algorithm — the more you log, the smarter your forecasts get.

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