Following the previous announcement, to give users an update on the progress and timeline for the migration to GRIB2 data format, ECMWF organised a session at the Using ECMWF’s Forecasts Event (UEF2026) next week on Thursday, 4 June 2026 at 10:30 – 11:20 CEST (09:30 – 10:20 BST). This session will be broadcast online, so you can follow along as well!
No need to fully register to follow the session. You can watch as a guest from the following link: Using ECMWF's Forecasts Event (UEF2026) | ECMWF
More information and the full programme can be found here.
Further information, including where to find the data and a detailed description of the static sample dataset and parameter changes, can be found in the Migration to GRIB edition 2 - Information page.
Following the session at UEF2026 in June, here is where the migration to GRIB edition 2 now stands.
ECMWF will introduce GRIB2 encoding for all real-time products with the implementation of IFS Cycle 50r2 with all output provided in GRIB2 only.
Some practical reminders while you prepare:
- Some parameters change units, including two groups of parameters that affect nearly everyone: the precipitation parameters move from metres to kg m⁻² (equivalent to millimetres of water), and the cloud cover parameters from a fraction to a percentage. The identifiers change too, so it is worth checking how your workflow selects and converts these fields. See changes to encoding of parameters for the full list.
- Some MARS requests will change, especially the param keyword, parameters archived with levtype=sol and levtype=hl, plus new timespan, chem and wavelength keywords. See Migration to GRIB2 - changes in the MARS language.
Everything is collected on the Migration to GRIB edition 2 Information page. To get updates as they happen, subscribe to the mailing list by sending an email to sympa@lists.ecmwf.int with the subject “SUBSCRIBE mtg2@lists.ecmwf.int”.