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 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.

On the map, click a metric label to bring that arrow to the front — handy when arrows overlap.

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:

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

With Surfnerd, no more "you should have been here yesterday"