The confidence score shows how closely other, independent weather models agree with the model that drives our forecast. When they agree, the forecast rests on firm ground and confidence is high. When they diverge, confidence drops.
What is compared
Our wave forecast is driven by Copernicus Marine (CMEMS) waves and DWD ICON-EU wind. We take that input exactly as the model produced it, before any corrections, and compare it hour by hour with two other global models: ECMWF and NOAA. If one of them is unavailable, the other still counts. The score never treats a missing model as agreement.
Five separate scores
Each hour gets a score from 0 to 100 for five things. 100 means the other models match the input; 0 means they are far off.
- Swell height
- Swell direction
- Period
- Wind speed
- Wind direction
The further the other models are from the input, the lower the score. When both ECMWF and NOAA are available, their scores are averaged.
The combined score
The combined confidence score blends the five scores into one number. Some count for more than others, and if one of them cannot be scored, the rest make up the combined score.
When there is no score
- Swell direction is not scored when the swell is very small, and wind direction is not scored when the wind is very light. In calm conditions the direction means little.
- If the other models are unavailable, there is nothing to compare with, so no score is shown. A missing model never counts as agreement.
What the score does not tell you
A high score means other models agree with our input; it does not guarantee the conditions will turn out that way, because the models can share the same blind spots. A low score is a warning that the input itself is uncertain.
Using confidence in practice
- High confidence: the forecast is reliable, plan around it.
- Moderate confidence: check back closer to the day for updates.
- Low confidence: treat the forecast as a rough outlook only.
The five separate scores show where the doubt lies. Low swell direction confidence, for example, means the swell angle may change, even if the wave height looks solid.