# Upcoming migration to GRIB2 data format

**URL:** <https://forum.ecmwf.int/t/upcoming-migration-to-grib2-data-format/15034>\
**Category:** Announcements\
**Tags:** ecmwf-updates, grib2\
**Created:** [29 May 2026 11:00 UTC](https://forum.ecmwf.int/t/upcoming-migration-to-grib2-data-format/15034 "2026-05-29T11:00:38Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Michela](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/898d66/32.png) [@Michela](https://forum.ecmwf.int/u/Michela)\
**Post date:** [29 May 2026 11:00 UTC](https://forum.ecmwf.int/t/upcoming-migration-to-grib2-data-format/15034/1 "2026-05-29T11:00:38Z")

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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](https://ecmwfevents.com/i/using-ecmwf-s-forecasts-uef2026/login)

More information and the full programme can be found [here](https://events.ecmwf.int/event/524/).

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](https://confluence.ecmwf.int/display/MTG2US/Migration+to+GRIB+edition+2+Information+page).

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**Author:** ![Michela](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/898d66/32.png) [@Michela](https://forum.ecmwf.int/u/Michela)\
**Post date:** [30 July 2026 12:09 UTC](https://forum.ecmwf.int/t/upcoming-migration-to-grib2-data-format/15034/2 "2026-07-30T12:09:42Z")

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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](https://confluence.ecmwf.int/spaces/MTG2US/pages/554148197/Migration+to+GRIB2+-+changes+to+encoding+of+parameters "https://confluence.ecmwf.int/spaces/MTG2US/pages/554148197/Migration+to+GRIB2+-+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](https://confluence.ecmwf.int/spaces/MTG2US/pages/621051006/Migration+to+GRIB2+-+changes+in+the+MARS+language "https://confluence.ecmwf.int/spaces/MTG2US/pages/621051006/Migration+to+GRIB2+-+changes+in+the+MARS+language").

Everything is collected on the [Migration to GRIB edition 2 Information page](https://confluence.ecmwf.int/spaces/MTG2US/pages/327661652/Migration+to+GRIB+edition+2+Information+page "https://confluence.ecmwf.int/spaces/MTG2US/pages/327661652/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](mailto:sympa@lists.ecmwf.int "mailto:sympa@lists.ecmwf.int") with the subject “SUBSCRIBE [mtg2@lists.ecmwf.int](mailto:mtg2@lists.ecmwf.int)”.