The forecast competition leaves its data open.
ECMWF released JJA 2026 forecast files and regional scores for an open framework comparing AI and hybrid subseasonal weather systems.
- Maturity
- Deployed, stage 4 of 4
- Support
- 2 sources · dataset
- Evidence detail
- How we know ↓
Communities and weather services need to know whether a promising model works at the lead times and in the regions they care about.
Forecast claims are hard to compare when systems use different variables, periods, and score definitions.
Participating machine-learning and hybrid systems made real-time forecasts under common rules for temperature, pressure, and precipitation.
What was shown, and what wasn’t
Shown
The public dataset covers common days 19–25 and 26–32 lead windows and publishes forecast files and regional scoring for JJA 2026.
Not shown · limits
- Benchmark skill does not make a forecast actionable in every region.
- A single season is not long-term operational validation.
- Warnings and public decisions remain institutional and human work.
Bright editorial interpretation
Shared evaluation lets weather agencies and researchers inspect where skill appears rather than relying on a single global headline.
Still open
How stable are rankings across seasons and extremes?
Which regions have too little observation data for confident scoring?
How will participating systems document revisions?
How we know2 sources · checked 2026-09-19 · no corrections
Original sources
- AI Weather Quest - Sub-seasonal forecasts ↗ · dataset
- JJA 2026 period - AI Weather Quest ↗ · dataset
Institutions: European Centre for Medium-Range Weather Forecasts
- Maturity
- Deployed
- Claim confidence
- high
- Event date
- 2026-09-14
- Source published
- 2026-09-14
- Captured
- 2026-09-19
- Last source review
- 2026-09-19
- Editorial method
- AI-assisted source review
- Place / relevance
- Global benchmark · global-study
Bright compared this account with the linked original and supporting sources and kept reported, budgeted, projected, and observed claims distinct. Bright did not independently audit the underlying records.
Maturity describes the tested or operational setting. Confidence describes support for the particular claim; one does not determine the other.
Revision & correction history
2026-09-19 · Initial open-benchmark draft.
No corrections recorded.
Keep exploring
Explore the shared question in another setting. These connections do not imply replication.