The confidence score reflects how much the underlying weather models agree with each other. When models converge on a similar outcome, confidence is high; when they diverge, confidence drops.
Ensemble spread
We compare the ECMWF ensemble mean against the spread (standard deviation) of its members, cross-referenced with the NOAA WW3 model. A tight spread means the models are confident; a wide spread signals uncertainty.
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.