# ERA5 data from 1st January 2025 was degraded and is being corrected **URL:** \ **Category:** C3S - Announcements\ **Tags:** c3s, cds, era5, global\_reanalysis, era5-land\ **Created:** [9 January 2025 12:24 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689 "2025-01-09T12:24:25Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Anabelle](https://forum.ecmwf.int/user_avatar/forum.ecmwf.int/anabelle/32/360_2.png) [@Anabelle](https://forum.ecmwf.int/u/Anabelle)\ **Post date:** [9 January 2025 12:24 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/1 "2025-01-09T12:24:25Z")
At the turn of 2025, an unfortunate technical issue with the production of ERA5 resulted in a large part of satellite observations not being used. This led to small but systematic differences, impacting mainly humidity in the tropics, and in lesser extent other ERA5 parameters as well from the 1st of January 2025 onwards. By the time the issue was discovered however, some ERA5T data from 1st of January 2025 had already been published in the Climate Data Store. This means that **the following ERA5T data sets have been affected from 1st January 2025 onwards:** **ERA5T and ERA5-Land-T hourly data:** - [ERA5 hourly data on single levels from 1940 to present](https://cds.climate.copernicus.eu/datasets/reanalysis-era5-single-levels?tab=overview) - [ERA5 hourly data on pressure levels from 1940 to present](https://cds.climate.copernicus.eu/datasets/reanalysis-era5-pressure-levels?tab=overview) - [Complete ERA5 global atmospheric reanalysis](https://cds.climate.copernicus.eu/datasets/reanalysis-era5-complete?tab=overview) - [ERA5-Land hourly data from 1950 to present](https://cds.climate.copernicus.eu/datasets/reanalysis-era5-land?tab=overview) **ERA5T daily data:** - [ERA5 post-processed daily statistics on single levels from 1940 to present](https://cds.climate.copernicus.eu/datasets/derived-era5-single-levels-daily-statistics?tab=overview) - [ERA5 post-processed daily statistics on pressure levels from 1940 to present](https://cds.climate.copernicus.eu/datasets/derived-era5-pressure-levels-daily-statistics?tab=overview) - [ERA5-Land post-processed daily statistics from 1950 to present](https://cds.climate.copernicus.eu/datasets/derived-era5-land-daily-statistics?tab=overview) **ERA5 and ERA5-Land monthly data is not affected.** **Other ERA5 related data:** - [Thermal comfort indices derived from ERA5 reanalysis (ERA5-HEAT)](https://cds.climate.copernicus.eu/datasets/derived-utci-historical?tab=overview) - [Agrometeorological indicators from 1979 to present derived from reanalysis (AgERA5)](https://cds.climate.copernicus.eu/datasets/sis-agrometeorological-indicators?tab=overview) **A solution is being implemented and the currently affected data will be corrected** in the final version that will be made available in about 2-3 months time. However, in contrast to what we have done in the past (e.g. in [October 2024](https://prod.ecmwf-forum-prod.compute.cci2.ecmwf.int/t/final-validated-era5-product-to-differ-from-era5t-in-july-2024/6685/1)) it was decided that **ERA5T will also be corrected** as we will overwrite the published ERA5T with the corrected version. So for ERA5 and ERA5-Land hourly data users will not need to wait for 3 months to pick up the corrected data. **That process has now started and we expect it to complete by early next week.** From that moment onwards, (re-)downloading ERA5T and ERA5-Land-T will contain the corrected datasets from the beginning of 2025. **Please watch this topic to be kept informed.** Please note that the [Climate Pulse application](https://pulse.climate.copernicus.eu/) is also affected by this issue. We are sorry for the inconvenience this may cause. Thank you for your patience. ECMWF Support on behalf of the Reanalysis team at ECMWF ---
**Author:** ![Anabelle](https://forum.ecmwf.int/user_avatar/forum.ecmwf.int/anabelle/32/360_2.png) [@Anabelle](https://forum.ecmwf.int/u/Anabelle)\ **Post date:** [14 January 2025 14:10 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/2 "2025-01-14T14:10:48Z")
We are pleased to inform our users that the ERA5T issue detailed above is fully resolved and that all degraded ERA5T has now been replaced. Users who downloaded ERA5T data from the datasets listed below for the period 1-4 January 2025 should download the data again. **ERA5T and ERA5-Land-T hourly data:** - [ERA5 hourly data on single levels from 1940 to present](https://cds.climate.copernicus.eu/datasets/reanalysis-era5-single-levels?tab=overview) - [ERA5 hourly data on pressure levels from 1940 to present](https://cds.climate.copernicus.eu/datasets/reanalysis-era5-pressure-levels?tab=overview) - [Complete ERA5 global atmospheric reanalysis](https://cds.climate.copernicus.eu/datasets/reanalysis-era5-complete?tab=overview) - [ERA5-Land hourly data from 1950 to present](https://cds.climate.copernicus.eu/datasets/reanalysis-era5-land?tab=overview) **ERA5T daily data:** - [ERA5 post-processed daily statistics on single levels from 1940 to present](https://cds.climate.copernicus.eu/datasets/derived-era5-single-levels-daily-statistics?tab=overview) - [ERA5 post-processed daily statistics on pressure levels from 1940 to present](https://cds.climate.copernicus.eu/datasets/derived-era5-pressure-levels-daily-statistics?tab=overview) - [ERA5-Land post-processed daily statistics from 1950 to present](https://cds.climate.copernicus.eu/datasets/derived-era5-land-daily-statistics?tab=overview) **Other ERA5 related data:** - [Thermal comfort indices derived from ERA5 reanalysis (ERA5-HEAT)](https://cds.climate.copernicus.eu/datasets/derived-utci-historical?tab=overview) Users of the [Agrometeorological indicators from 1979 to present derived from reanalysis (AgERA5)](https://cds.climate.copernicus.eu/datasets/sis-agrometeorological-indicators?tab=overview) dataset will need to wait for a further update before downloading the data again. Thank you for your patience. ECMWF Support on behalf of the Reanalysis team at ECMWF ---
**Author:** ![Anabelle](https://forum.ecmwf.int/user_avatar/forum.ecmwf.int/anabelle/32/360_2.png) [@Anabelle](https://forum.ecmwf.int/u/Anabelle)\ **Post date:** [15 January 2025 16:52 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/3 "2025-01-15T16:52:09Z")
Please note the affected time period has been revised and confirmed to be 1-6 January, 2025. Our [ERA5 Documentation](https://confluence.ecmwf.int/x/wv2NB) has been updated accordingly. We will post a further update about the [Agrometeorological indicators from 1979 to present derived from reanalysis (AgERA5)](https://cds.climate.copernicus.eu/datasets/sis-agrometeorological-indicators?tab=overview) dataset by early next week. ECMWF Support on behalf of the Reanalysis team at ECMWF ---
**Author:** ![Mark\_Elliott1](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/c68b51/32.png) [@Mark\_Elliott1](https://forum.ecmwf.int/u/Mark_Elliott1)\ **Post date:** [16 January 2025 09:00 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/4 "2025-01-16T09:00:16Z")
Hi Anabelle, Now that the affected period is1-6 Jan, did you re-run ERA5-T again, or were those extra 2 days (5th and 6th) captured in the first re-run? I re-downloaded my elements for all of Jan yesterday - will I have the new revision for 5th and 6th or do I need to repeat the task? Thanks Mark ---
**Author:** ![Anabelle](https://forum.ecmwf.int/user_avatar/forum.ecmwf.int/anabelle/32/360_2.png) [@Anabelle](https://forum.ecmwf.int/u/Anabelle)\ **Post date:** [17 January 2025 10:21 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/5 "2025-01-17T10:21:25Z")
Hi Mark, Those extra 2 days (5th and 6th) were captured in the first re-run. Apologies for the confusion this may have caused. ---
**Author:** ![Mark\_Elliott1](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/c68b51/32.png) [@Mark\_Elliott1](https://forum.ecmwf.int/u/Mark_Elliott1)\ **Post date:** [17 January 2025 10:34 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/6 "2025-01-17T10:34:05Z")
Thank you Anabelle, That’s good news ---
**Author:** ![user326](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/u/a6a055/32.png) [@user326](https://forum.ecmwf.int/u/user326)\ **Post date:** [27 January 2025 10:01 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/7 "2025-01-27T10:01:51Z")
Hi Anabelle, I just applied ERA5 hourly data on single levels from 1940 to present.About how long it takes to get through Thanks Lin Feng ---
**Author:** ![Anabelle](https://forum.ecmwf.int/user_avatar/forum.ecmwf.int/anabelle/32/360_2.png) [@Anabelle](https://forum.ecmwf.int/u/Anabelle)\ **Post date:** [29 January 2025 10:35 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/8 "2025-01-29T10:35:45Z")
The impacted dates in the [Agrometeorological indicators from 1979 to present derived from reanalysis (AgERA5)](https://cds.climate.copernicus.eu/datasets/sis-agrometeorological-indicators?tab=overview) dataset have been reprocessed and now available to download from the CDS. **Users are advised to download the data again (tagged v1.1.1 in the filename).** Daily update of the dataset has now also resumed. Apologies for the delay to make the reprocessed data available. ECMWF Support ---
**Author:** ![Mark\_Elliott1](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/c68b51/32.png) [@Mark\_Elliott1](https://forum.ecmwf.int/u/Mark_Elliott1)\ **Post date:** [29 January 2025 17:17 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/9 "2025-01-29T17:17:54Z")
Hi Anabelle. _“have been reprocessed and now available to download from the CDS”_ Is that just the Jan data, or the agERA5 you informed me “_the new regenerated AgERA5 data will be made available in early 2025_” - ticket CUS-23138 Thanks, Mark ---
**Author:** ![Anabelle](https://forum.ecmwf.int/user_avatar/forum.ecmwf.int/anabelle/32/360_2.png) [@Anabelle](https://forum.ecmwf.int/u/Anabelle)\ **Post date:** [29 January 2025 17:38 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/10 "2025-01-29T17:38:12Z")
Hi Mark, Only talking about the January data (1-6 January 2025) in this topic 🙂 AgERA5 is produced using ERA5T - if an issue is identified in ERA5T (as it was the case in early January and described in this forum topic) then it affects AgERA5. With ERA5T being corrected, AgERA5 needed to be corrected also for those few days. Thanks, Anabelle ---
**Author:** ![Mark\_Elliott1](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/c68b51/32.png) [@Mark\_Elliott1](https://forum.ecmwf.int/u/Mark_Elliott1)\ **Post date:** [29 January 2025 17:45 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/11 "2025-01-29T17:45:33Z")
Thanks Anabelle, Just me misunderstanding what had been reprocessed - or maybe just being too hopeful 🙂 Thanks anyway, M ---
**Author:** ![John\_Barrera](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/j/9dc877/32.png) [@John\_Barrera](https://forum.ecmwf.int/u/John_Barrera)\ **Post date:** [16 September 2025 11:11 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/12 "2025-09-16T11:11:57Z")
Hi folks: looks like some data bases are not visible fron the API: for dataset = “derived-utci-historical”: HTTPError: 404 Client Error: Not Found for url: [https://ads.atmosphere.copernicus.eu/api/retrieve/v1/processes/derived-utci-historical](https://ads.atmosphere.copernicus.eu/api/retrieve/v1/processes/derived-utci-historical) process not found dataset derived-utci-historical not found ---
**Author:** ![Kevin\_Marsh](https://forum.ecmwf.int/user_avatar/forum.ecmwf.int/kevin_marsh/32/368_2.png) [@Kevin\_Marsh](https://forum.ecmwf.int/u/Kevin_Marsh)\ **Post date:** [16 September 2025 19:38 UTC](https://forum.ecmwf.int/t/era5-data-from-1st-january-2025-was-degraded-and-is-being-corrected/10689/13 "2025-09-16T19:38:59Z")
hi John, It looks like you are using the url for the wrong data store (ADS) - this UTCI dataset is on the CDS, so you get the ‘not found’ error message.