How the calmness score works

The 0–100 calmness score

A score of 100 = perfectly calm. The number is computed for every beach, every hour, by combining Open-Meteo wind, gust and wave data with the beach's own orientation and shelter.

1. 1. Onshore factor

   Measures how directly the wind is blowing into the face of the beach.

   • 1 = wind straight from the sea the beach faces (worst for calm water)
   • 0 = wind from the opposite direction, offshore (best)

2. 2. Effective wind

   Wind speed adjusted for direction and shelter.

   directional = 0.35 + 0.6 × onshoreFactor
   effectiveWind = windSpeed × directional × (1 - shelter × 0.55)
   gustKick = max(0, windGusts - windSpeed) × 0.4 × directional × shelterFactor
   felt = effectiveWind + gustKick

   Headlands and enclosed coves absorb fetch and swell through the shelter factor. The base directional bias is 0.35, so even fully offshore winds still ruffle the surface a little.

3. 3. Swell contribution

   swell = (waveHeight or windSpeed / 55) × (0.55 + steepness × 0.9) × (1 - shelter × 0.6)

   Open-Meteo provides wave height when available; otherwise it is estimated from wind speed. Steep beaches amplify swell; sheltered beaches reduce it.

4. 4. Final score

   score = 100 - (0.85 × felt + 0.012 × felt²) - swell × 20

   The wind penalty is quadratic, so light winds barely hurt the score while strong winds hurt a lot. The score is capped between 0 and 100.