Dear user,
Welcome to the December edition (Nr. 6) of the Data Support News!
As ever, we're pleased to share recent developments to help you stay ahead of key changes. A copy of each update is also shared in the ECMWF Forum and shared in our Data & Charts blog for future reference.
The introduction of the Release Candidate Phase (RCP) for IFS Cycle 50r1 is planned for late January 2026.
From January 2026, Cycle 50r1 forecast production will run in parallel with the operational system, giving users time to test the new output and prepare their workflows.
Cycle 50r1 includes major scientific and technical updates across the model, data assimilation, coupling, and forecast systems. These enhancements cover the ocean, sea ice, wave and atmospheric components, along with several technical configuration changes. There are no changes to horizontal, vertical or temporal resolution in this cycle.
Following the alignment of the high-resolution forecast (HRES) and the ENS control in Cycle 49r1, Cycle 50r1 will introduce a structural adjustment: the current ENS control will no longer be produced, and the data stream previously known as HRES will become the new ENS control.
More information on the upgrade can be found here: https://confluence.ecmwf.int/display/FCST/Implementation+of+IFS+Cycle+50r1
Users with an ECMWF Service Agreement are strongly encouraged to register their host configuration details to receive test products via dissemination: https://confluence.ecmwf.int/display/DAC/RCP+50r1+-++Test+System+User+Details. Your early completion of this form will expedite the process in January 2026. Note, however, that changes to hosts and destinations will be paused for the festive period (see below).
For any questions, please reach out to us via the ECMWF Support Portal.
As per previous years, the Product Requirements Editor (PREd) will enter a read-only mode from 18 December 2025 to 5 January 2026. ECPDS will remain accessible to those with existing access, but host and destination changes will not be completed during the freeze period.
During this period, no new requests or modifications to data requirements, service agreements, hosts or destinations can be made. We encourage users to submit required changes before the freeze with sufficient time for Data Support to assist you. We thank you for your patience during this busy period.
To support your planning, we have included a simple calendar reminder with the freeze dates. (PREd_Freeze_Announcement_2025-2026.ics)
ECMWF Data Support Team will also be limited in capacity between 18 December 2025 and 05 January 2026. 24/7 support for operational issues remains available, but please note that configuration changes will not be made during this period.
We are working towards releasing the subseasonal forecast slightly earlier in the day.
A new pre-schedule system is under preparation for those who are eligible for pre-schedule delivery and will become active soon, subject to final validation.
More information will be shared once timings are confirmed.
ECMWF will soon extend the dissemination of the Seasonal Forecast system (SEAS5) to include 13 months of forecast data once per quarter (February, May, August and November). The first delivery is scheduled for February 2026.
Users who do not have access to PREd need to open a ticket through ECMWF Support Portal and request this change. Changes in volume may require an amendment to your Service Agreement if exceeding the current contractual volume limit.
This enhancement will be added to the Product Requirements Catalogue and as PREd snippets shortly, and further details will follow in a future update.
Please note that the extension data (months 8-13) will only be provided in the new ECMWF or WMO file-naming convention templates: File naming convention and format for real-time data
Following the removal of the Information Cost on 1 October 2025, the transition to Open Data continues to progress well. Users report smoother ordering workflows, and ECMWF has observed increased adoption of the IFS and AIFS Open Datasets. We also recently added three new parameters: Total cloud cover (tcc), Snow depth (sd) and Snowfall (sf) to the IFS Open Dataset.
For example, in June 2025, users downloaded around 100 million files totalling 833 TB. By November 2025, this had risen to roughly 200 million downloads and 1,292 TB, based on figures from the ECMWF Free & Open Data Portal: https://data.ecmwf.int/ (not including data retrieved from AWS, Azure or Google Cloud).
To help visualise the data access and licence structure, including where Free and Open Data sits, please refer to the attached image ECMWF_Free_Open_Data.png.
We thank all users for their constructive engagement throughout this transition.
All ECMWF Products from the Real-time Catalogue now fall under the CC-BY-4 licence. A clear attribution is legally required when using or sharing the data, whether accessed from our free data portal, via a Service Agreement, or from a third party.
Guidelines for attributing and citing ECMWF Products can be found here: Attributing and citing ECMWF data
A recommended format for the attribution is:
ECMWF IFS Forecast data, accessed from ECMWF's MARS archive, © European Centre for Medium-Range Weather Forecasts (ECMWF), 2025. Licensed under CC-BY-4.0.
Please also note that users who redistribute or broker ECMWF Products are responsible for assisting users who access data via their services.
The final date for issuing invoices in 2025 will be: 11 December 2025
If you require an invoice in the coming weeks, please raise a ticket in the ECMWF Support Portal by 10 December 2025.
Any requests created after this date will be invoiced in 2026.
As always, we're here to support your data operations and provide clarity around changes that may affect your setup. Should you have any questions, don't hesitate to reach out via the ECMWF Support Portal.
We hope you've found these news items useful over the past year and would welcome your feedback on what improvements we could make. If you'd like to share this information, please feel free to raise a ticket in the ECMWF Support Portal.
We wish you all a pleasant festive period and look forward to working with you in 2026!
Best wishes,
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ECMWF Data Support Team
European Centre for Medium-Range Weather Forecasts
Reading, UK | Bologna, Italy | Bonn, Germany
ECMWF Support Portal | ecmwf.int
