OpenIFS now open source

ECMWF has made its portable global forecasting model, OpenIFS, fully open source for the first time, marking a significant step in its commitment to open science and collaboration.

OpenIFS is a research, education and training version of the Integrated Forecasting System (IFS). Developed over decades, the IFS is a shared achievement of ECMWF’s Member and Co-operating States, built through sustained investment, scientific excellence and operational expertise. Its evolution has been shaped by close collaboration with national meteorological services, notably Météo-France, with which ECMWF has co-developed the IFS/ARPEGE system for nearly 40 years.

Until now, OpenIFS has been available under licence, typically through institutions. By removing this requirement, ECMWF is opening access to a much wider community of users.

The move simplifies access and removes administrative barriers, enabling researchers, educators and developers to work more freely with the model. Users can now download, modify and run the code without restriction, including on local systems such as laptops. This flexibility supports a broader range of applications, from academic research and teaching to exploratory development and industry collaboration.

Making OpenIFS open source also strengthens scientific transparency and reproducibility. Researchers can cite the exact version of the code used in their work and share it alongside publications, including in open-access journals. At the same time, all users will have access to a consistent and up-to-date version of the model, supporting more robust comparisons and collaboration across institutions.

The change will help bring OpenIFS closer to the operational IFS. While the operational system is updated annually, OpenIFS releases have historically lagged behind. Open sourcing the model will enable more frequent updates and reduce the gap between research and operations, ensuring that users can work with code that more closely reflects the current forecasting system.

Since its launch in 2011, OpenIFS has supported a growing international community of users. It has become widely used in universities for teaching numerical weather prediction and atmospheric modelling, helping to bridge the gap between theory and practical application. The model has also contributed to a range of research activities, including climate and atmospheric modelling and atmospheric composition research.

OpenIFS has already demonstrated value beyond education and research. It has supported developments that improve computational efficiency and has contributed to innovations that feed back into operational forecasting. By making the model openly available, ECMWF aims to accelerate this cycle of innovation and strengthen links between research and operations.

The transition to open source also aligns ECMWF with broader practices across the global weather and climate community, where open models are increasingly used to foster collaboration and innovation.