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ECMWF is bringing forward the full transition to open data by an entire year, to 1 October 2025, marking a significant milestone in its commitment to making weather data more accessible and impactful.
The change means that the entire ECMWF Real-time Catalogue will be fully available under a CC-BY-4.0 licence at the maximum resolution, removing the Information Cost (data cost) for all users.
Data produced by the Integrated Forecasting System (IFS) and the Artificial Intelligence Forecasting System (AIFS) will then all be open at their full native resolution with no data cost, further expanding access to high-quality numerical weather prediction products.
The change complements existing ECMWF open datasets, such as the Archive Catalogue and Open Charts. It also aligns with broader global trends towards open meteorological data and supporting global initiatives, such as the Early Warning for All initiative of the World Meteorological Organization (WMO) and the United Nations Office for Disaster Risk Reduction (UNDRR).
Timeline of transition
In December 2019, ECMWF’s Council and its Member and Co-operating States approved a phased transition from a restricted data policy to a fully open data policy, starting from 2020 with the goal of achieving this in 2026.
Since then, ECMWF has made significant steps to make more data available openly and freely. It has also reduced the costs of data while providing tiered access to services to reduce the barriers to entry.
This timeline shows a series of steps on the road to open data since 2020.
What’s changing?
The change in October 2025 can be summarised as follows:
- No more data costs: The entire ECMWF Real-time Catalogue will be under a CC-BY-4.0 licence, eliminating the Information Cost. The licence will allow the re-use and redistribution of data and thus the creation of new services.
- Service charges remain for high-volume users: While the full catalogue is open, service charges will still apply for enhanced delivery services and custom access needs.
The impact of early implementation
The decision to accelerate the transition to open data reflects ECMWF’s confidence in the open data model and its ability to support scientific, commercial, and operational users worldwide.
By moving to full implementation in 2025 rather than 2026, ECMWF is enabling earlier access to high-resolution data, supporting research, innovation, and operational forecasting for a broad range of users.
The shift to open data has already demonstrated significant benefits, with open data usage continuing to grow rapidly and the range of industries using it widening. Since expanding free and open datasets, ECMWF has seen a 150% increase in open data retrievals, with the ECMWF Data Portal now serving approximately 680 TB per month. Access through third-party providers such as Open-Meteo, Amazon, Google, and Microsoft further extends global reach.
At the same time, high-volume use with a service charge remains a crucial part of ECMWF’s data ecosystem. The number of high-volume licensed users has grown by 46% during the open data transition since 2020, reflecting strong demand for specialised services and operational forecasting support.
The transition builds on previous steps, such as making AIFS data openly available in 2024 and progressively increasing the resolution of free and open datasets. This next phase completes the transition, ensuring seamless, unrestricted access to ECMWF’s forecasting products for all.
It enshrines the commitment of ECMWF and its Member States to open policies fostering re-use of data and collaboration for the broader benefit of society.
Further details on how to access the full ECMWF Real-time Catalogue will be provided ahead of the transition in October 2025.