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ECMWF opens the full Real-time Catalogue to all users

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ECMWF opened its full Real-time Catalogue under CC BY 4.0 on Oct 1, 2025. Here is what changed, what still depends on delivery channels, and how GribStream users should read the news.

On October 1, 2025, ECMWF opened access to its full Real-time Catalogue, making the complete real-time product catalogue available to all users under a Creative Commons BY 4.0 license. Previously, only a limited open subset was freely accessible. ECMWF removed data charges, while delivery services may still incur cost recovery fees.

What changed

  • Full Real-time Catalogue is now open to everyone (not just member-state users).
  • The data are available under CC BY 4.0, enabling broad reuse with attribution.
  • ECMWF plans to extend the free subset in 2026 from about 25 km resolution to 9 km for part of the catalogue.

ECMWF had already announced in March 2025 that it was bringing the final open-data transition forward by a year, from 2026 to October 1, 2025. The October announcement is the operational milestone: the full Real-time Catalogue is open under the license, and the previous "Information Cost" barrier is removed.

The distinction that matters for data users is license versus delivery. Open means ECMWF no longer restricts reuse of the Real-time Catalogue products beyond CC BY 4.0 attribution. It does not mean every high-volume product is available instantly and free of delivery cost through every access channel. ECMWF says the free online subset remains a practical subset, while larger or faster access paths may still involve service or distribution charges.

Why it matters

For teams consuming ECMWF guidance, open access reduces friction for evaluation and research workflows. It also makes it easier to compare deterministic and ensemble products across ECMWF's ecosystem without licensing barriers.

That is particularly important for organizations that blend multiple global models. A forecasting product can now compare ECMWF IFS, ECMWF AIFS, NOAA GFS, NOAA AI-GFS, and ensemble guidance without treating ECMWF's license boundary as a separate commercial gating issue. For ML and verification workflows, it also makes it easier to explain provenance: the data can be reused commercially, but attribution remains part of the license.

The 2026 free-subset expansion is also worth watching. ECMWF says the open subset is expected to include 9 km forecasts later in 2026 with a 2-hour latency. That would narrow the gap between "open and easy to fetch" and "full catalogue but high-volume delivery service" for many downstream users.

What this means for GribStream users

GribStream already supports ECMWF-family datasets such as IFS Operational, IFS Ensemble, IFS Wave, AIFS Oper, and AIFS Ensemble. The open-catalogue change is good news for GribStream customers, but it should be read carefully:

  • It lowers the licensing friction around ECMWF reuse and redistribution.
  • It does not automatically mean every Real-time Catalogue parameter appears in the public cloud feeds GribStream ingests on day one.
  • It makes ECMWF coverage easier to expand when the relevant products are available through reliable public distribution channels.
  • It gives teams a cleaner basis for comparing ECMWF-family datasets against NOAA datasets in the same API workflow.

The difference showed up clearly again during the May 2026 ECMWF cycle change. ECMWF's IFS 50r1 and AIFS v2 rollout changed operational model versions and AIFS parameters, while GribStream tracked the public feed boundary separately in IFS 50r1 now on GribStream. The license may be open, but API availability still depends on the exact product streams that are published and stable enough to ingest.

For customers, the practical takeaway is simple: use the GribStream model pages as the live inventory of what is currently queryable, and treat ECMWF's Real-time Catalogue as the upstream universe that can become reachable as open distribution improves.

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