CDS performance issue resolved following maintenance session of January 8 2024


Update on 12-Jan-2024: The cause of the performance issue has been identified and addressed. Access to affected datasets (e.g. ERA5, seasonal forecast data, etc) has been restored. The backlog of queued requests remains large however but we hope the system will catch up over the weekend so that normal operations can resume early next week. Thank you for your patience.

Update on 11-Jan-2024: Performance issues continue and are now also affecting access to datasets stored in the MARS archive (e.g. Seasonal forecast data, CERRA, ERA5-complete, ...). Meanwhile the number of queued requests keeps increasing. For the benefit of all users, we ask that users refrain from submitting further requests at this time. Thank you for your cooperation and understanding.

Update on 10-Jan-2024: There are performance issues, affecting ERA5 downloads in particular. The CDS team is actively working at restoring full access.

Update on 09-Jan-2024: Service maintenance session successfully completed. CDS system is operational but the backlog of queued requests is currently impacting performance. Thank you for your patience.

A service maintenance session is planned on the Climate Data Store (CDS) on Monday, January 8, 2024 from 09:30am to 12:30pm UTC.

During this time period, submitted requests will be queued until the end of the service maintenance session. To avoid a large backlog of queued requests for submission from the early afternoon, we would recommend users to not submit requests from 09:30am to 12:30pm UTC on Monday, January 8th, 2024.

Users may also check the ECMWF systems (including CDS) status page at

We encourage users to "Watch" this page to receive email notifications of updates on this announcement.

ECMWF Support