Gas storage forecast · track recordWhat we forecast, and what actually happened
Every past forecast is scored against the reported AGSI+ fill level for its date, reconstructed from committed git history. The numbers are reproducible and were never tuned after the fact.
In brief
Across 7 countries and 22,099 scored forecasts, 68% to 92% of outcomes fell inside the 80% range, depending on the country (scored through 21 October 2026). The mean absolute error was 0.80 to 1.26 percentage points of fill level.
Archived input error: 3 September 2026
The forecast issued on 3 September used a corrupt storage observation above 40,000% and reached the model ceiling of 100%. For 16 September, reported fill was 55.98%, a 44.02 percentage-point miss. This forecast remains in the track record and its aggregate scores. Input validation now rejects such observations before modelling and publication.
The scored point forecast can differ from the simulated P50 median. Source observations may subsequently be revised.
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Questions and answers
- What does coverage mean?
- The share of realised fill levels that fell inside the forecast's P10–P90 band. A calibrated band covers about 80%; much more means the band is wider than it needs to be, much less means it is too narrow.
- Which forecast is scored when the data updates twice a day?
- The first forecast published on each day, as before the evening update existed. The evening build has seen one more day of data, so scoring it would flatter short-range accuracy.
- Why does the forecast start before today?
- AGSI+ publishes each gas day with a delay of one to two days. The model estimates those unpublished days first (the light grey segment in the chart), then forecasts 14 days from today.
- What does the 80% range mean?
- It is the band between the 10th and 90th percentile (P10–P90) of the model's simulated paths: eight out of ten outcomes should fall inside it. Whether they do is checked every day on the track record page.