CDSAPI limitations and restrictions


Hello. Two questions about the CDSAPI:

  • Is there any kind of limitation or restriction (max number of simultaneous requests, max num fields / period / size limitation per request,...) in the CDSAPI usage like happens in ECMWFAPI?
  • Is there any way to check the CDSAPI global queue in order to estimate the current queue delay, like happens in ECMWFAPI?

Thanks in advance,


Hi Oriol,

Yes, there are restrictions applied to the CDS (and the CDS API). Our technical team monitors the system load continuously and may make adjustments. Hence it is difficult to give a clear picture now.

  • For ERA5 hourly data on the CDS, a request is limited to 120,000 fields.
  • For ERA5 monthly data on the CDS, a request is limited to 10,000 fields.

Indeed, the feature for users to check the CDS global queue is on our TODO list. We hope to make our system more transparent to our users. However, at the time, I'm not at a position to give you a date when this can be implemented. Thank you for your understanding.

Kind regards,


Hi Oriol,

Some more information re: the number of fields/size limit.

There is a 'number of items' limit set for each dataset.  An item is the 'basic unit' of the dataset, and the size of your request will be checked against the dataset limit.

This limit varies from dataset to dataset, as it depends on the granularity of the data served. For ERA5, 1 'item' corresponds to 1 variable on a (2D) field at 1 level at 1 timestep.

So a request for 2m temperature for 1 day would correspond to 1 (variable) x 1 (level) x 24 (hourly timesteps) = 24 'items'



Thank you Kevin, very useful information.