Forecast lab
How sure is the forecast?
A weather forecast isn't one answer. Forecast centers run a model dozens of times from slightly different starting points, an ensemble, and the spread of those runs tells you how confident to be. Below are today's 15-day ensembles from ECMWF's machine-learning model (AIFS), its traditional physics model (IFS), and NOAA's GEFS.
Loading today's ensembles…
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Across the region
The same models on a map: press play to watch the next 10 days, switch to AIFS − IFS to see where the machine-learning model and the physics model disagree, or click anywhere to see that spot's ensemble forecast above.
Map loads when you scroll here…
How did the models do?
Every day each model forecasts the week ahead. Here are those forecasts, made 1 to 7 days in advance, checked against what actually happened (ERA5, ECMWF's reconstruction of past weather) for the same place as above.
Show errors as a table
Reading the chart
- Solid line: the median run. Shaded band: where the middle 80% of runs fall.
- A narrow band means the runs agree. Watch it widen after a few days: that's chaos at work.
- AIFS is ECMWF's data-driven model, trained on decades of reanalysis. Where it and IFS disagree is where it gets interesting.
Data: ECMWF AIFS, IFS and ERA5 (CC BY 4.0) and NOAA GEFS and GFS, via Open-Meteo.