A portable version of the global model used by ECMWF to produce medium-range weather forecasts is being made openly available to all for the first time.
The OpenIFS model, a version of the Integrated Forecasting System (IFS) used for research, education and training, has, until now, only been available for use under licence, for example within an institution.
Now, ECMWF is making OpenIFS’s forecasts fully open source, marking another major step in the Centre’s commitment to open science.
Increasing accessibility and collaboration
The move will make it easier to collaborate and generate new ideas, with all users having access to the same version of the data.
Florian Pappenberger, ECMWF Director-General, said: “Opening the model will broaden access, deepen collaboration and accelerate innovation across our community.
“Making OpenIFS open source is a natural and strategic step for ECMWF. The Integrated Forecasting System is a shared achievement of our Member and Co-operating States, built on scientific excellence, operational expertise and sustained long-term investment.
“From its early development with Météo-France to today’s wide network of national meteorological services and research partners, the IFS has always been a collective endeavour. This step reinforces ECMWF’s role as trusted partner, while empowering our community to continue advancing this shared asset.”
Virginie Schwarz, President and CEO of Météo-France, added: "Météo-France and ECMWF have been working closely together on the development of the IFS/Arpège code for nearly 40 years. Today, more than 50 versions later, our forecasts are continuously improving, enabling ECMWF and Météo-France to build their support and services around the most powerful code in the world. We are proud to now share our model more widely with the international community by making IFS/Arpège available."
Supporting workflows
By removing the bureaucracy often involved with obtaining a licence, allowing users to modify code as required, and even being able to run the OpenIFS model on a laptop, researchers can also now cite the code they have used in publications. The software will be available without restrictions, for example as part of open-access journal papers, and everyone will have access to a more up-to-date version of the IFS.
Mike Sleigh, Head of Integrated Forecast Systems at ECMWF, said: "Making the OpenIFS forecast model open source will support reproducible research, but, just as importantly, will help OpenIFS users stay current. The IFS updates annually, but OpenIFS releases have, until now, been less frequent. Going open source will help us to keep OpenIFS much closer to the operational version of the IFS, providing up-to-date code and avoiding the lag between research and operations.”
A growing community
Since the inception of OpenIFS in 2011, a growing user community has benefited from the project, which has enabled new collaborations, increased research and training opportunities in universities, and created an international scientific workshop series.
Now, as Marcus Koehler, ECMWF Scientist on the OpenIFS project, explains, OpenIFS’s reach goes beyond university students and researchers: “OpenIFS has become a popular teaching tool for numerical weather prediction and modelling at universities across Europe but the change to open source, which follows the open-source model used at other global weather centres, really provides true open access to anyone, for any purpose, including the potential for industry collaboration.”
OpenIFS has already had significant successes in making savings in computing resources at ECMWF for operational forecasting. It has also been an excellent tool to bridge the gap between theoretical teaching and the practical experience of using a world-leading forecast model and enabling scientists to contribute to atmospheric research.
Going open source will increase innovation opportunities and as Adrian Hill, ECMWF Senior Scientist and OpenIFS project lead, says, continue to strengthen the collaboration between ECMWF and the scientific community: “For 15 years, the OpenIFS project has fostered a dynamic and growing community of users applying the model to an extensive range of atmospheric, climate, and educational activities: the EC-Earth4 climate model, the development of single-precision IFS, research with idealised atmospheric modelling and composition modelling, to name a few. The release of the data on GitHub today (5 March 2026) will enable further innovation and continue to build the strong collaboration made possible by OpenIFS.”
Access OpenIFS
The OpenIFS model source code is available on GitHub, alongside documentation and guidance.