CDS API syntax

The details offered in this page are intended to explain the different selection options for each of the C3S seasonal forecast datasets. For users of the CDS API the following information is relevant:

  • API 'dataset' name: it is shown in brackets alongside the full title.
  • API 'request' details: each widget corresponds to one keyword in the API 'request' which shall be formed by the name of the widget in "snake case" (https://en.wikipedia.org/wiki/Snake_case).
    Example: "Originating centre" would be originating_centre in the CDS API 'request'

Daily data

You will find two CDS catalogue entries labelled 'daily data'; these contain data at daily or subdaily frequency (6h, 12h or 24h) . The output of the different forecasting systems is available both for real-time forecasts (from 2017 onwards) and retrospective forecasts (referred to as hindcasts) at least for the period 1993-2016.
Note that all available individual members for each forecasting system will be provided with every request.

One dataset contains surface (or single level) parameters, the other contains variables on 12 pressure levels spanning 1000 hPa to 10 hPa.


01. Originating centre

Select the name of the institution the forecasting system of your interest originates from.

02. System

Select the version of the forecasting system. This is a numeric label and the available values are different for the different "originating centres". Note that for a given start date you could find more than one system available for a single "originating centre".
Please note that you must pair up your forecasts with the relevant hindcasts by using the same "system" for both of them. A full description of the use of the system keyword is available from the "Documentation" tab.

03. Variable

Select the parameter(s) you are interested in.

04. Year

Select the year of the initialization date of the model run(s) you are interested in.
Note that years in both the hindcast period and real-time forecasts are shown here together. You can find more details about hindcast and forecast years availability in the Start dates available in the CDS per forecast system page.

Please note that you must use the hindcast data in order to make a meaningful use of the forecast data. And remember you must pair forecasts and hindcasts up by using the same "system" for both of them.

05. Month

Select the month of the initialization date of the model run(s) you are interested in.

06. Day

Select the day of the initialization date of the model run(s) you are interested in.
Note that due to different production schedules, the available dates may differ between hindcasts and forecasts and between "originating centres".
You can find more details about the production schedules in the Description of the C3S multi-system table.

07. Leadtime hour

Select the lead time(s) you are interested in. This is the time, in hours, from the initialization date.
Bear in mind that some variables are available every 6 hours, and some every 24 hours. You will find that information in the full list of available parameters from the "Documentation" tab and also in the summary table shown in the "Overview" tab of this CDS dataset.
Note that the length of the outputs is at least 6 calendar months, but it may not be the same for all "originating centres".

08. Geographical area

You can select a global field ("whole available area") or a regional subselection by providing the latitude and longitude of its corners

09. Data format

You can select the data format for your data retrieval.
Currently, GRIB format is used to store C3S seasonal forecast datasets data files.
An experimental netCDF conversion can be also accessed. You can find some related information in the "Documentation" tab.

10. Terms of use

You must accept the terms and conditions of the Copernicus User Licence in order to access the C3S seasonal forecast data.

01. Originating centre

Select the name of the institution the forecasting system of your interest originates from.

02. System

Select the version of the forecasting system. This is a numeric label and the available values are different for the different "originating centres". Note that for a given start date you could find more than one system available for a single "originating centre".
Please note that you must pair up your forecasts with the relevant hindcasts by using the same "system" for both of them. A full description of the use of the system keyword is available from the "Documentation" tab.

03. Variable

Select the parameter(s) you are interested in.

04. Pressure level

Select the pressure level(s) for the variables you are interested in.

05. Year

Select the year of the initialization date of the model run(s) you are interested in.
Note that years in both the hindcast period and real-time forecasts are shown here together. You can find more details about hindcast and forecast years availability in the Start dates available in the CDS per forecast system page.

Please note that you must use the hindcast data in order to make a meaningful use of the forecast data. And remember you must pair forecasts and hindcasts up by using the same "system" for both of them.

06. Month

Select the month of the initialization date of the model run(s) you are interested in.

07. Day

Select the day of the initialization date of the model run(s) you are interested in.
Note that due to different production schedules, the available dates may differ between hindcasts and forecasts and between "originating centres".
You can find more details about the production schedules in the Description of the C3S multi-system table.

08. Leadtime hour

Select the lead time(s) you are interested in. This is the time, in hours, from the initialization date.
Note that the length of the outputs is at least 6 calendar months, but it may not be the same for all "originating centres".

09. Geographical area

You can select a global field ("whole available area") or a regional subselection by providing the latitude and longitude of its corners.

10. Data format

You can select the data format for your data retrieval.
Currently, GRIB format is used to store C3S seasonal forecast datasets data files.
An experimental netCDF conversion can be also accessed. You can find some related information in the "Documentation" tab.

11. Terms of use

You must accept the terms and conditions of the Copernicus User Licence in order to access the C3S seasonal forecast data.

Monthly data

Outputs from the atmospheric component of the forecasting systems

You will find two CDS catalogue entries for monthly statistics: monthly average, minimum, maximum and standard deviation are available for all initialization dates. Additionally, for real-time forecast initialization dates you will find the ingredients to calculate the forecast monthly anomalies: the forecast ensemble mean and the hindcast climate mean. The output of the different forecasting systems is available both for real-time forecasts (from 2017 onwards) and retrospective forecasts (referred to as hindcasts) for the period 1993-2016.

One dataset contains surface (or single level) parameters, the other contains variables on 11 pressure levels spanning 925 hPa to 10 hPa.


01. Originating centre

Select the name of the institution the forecasting system of your interest originates from.

02. System

Select the version of the forecasting system. This is a numeric label and the available values are different for the different "originating centres". Note that for a given start date you could find more than one system available for a single "originating centre".
Please note that you must pair up your forecasts with the relevant hindcasts by using the same "system" for both of them. A full description of the use of the system keyword is available from the "Documentation" tab.

03. Variable

Select the parameter(s) you are interested in.

04. Product type

Select the monthly product you are interested in.
Note that the products under the category "Individual members" consist of all available individual ensemble members, while those in the category "Ensemble" have a single value for each forecast system ensemble.

05. Year

Select the year of the initialization date of the model run(s) you are interested in.
Note that years in both the hindcast period and real-time forecasts are shown here together. You can find more details about hindcast and forecast years availability in the Start dates available in the CDS per forecast system page.

Please note that you must use the hindcast data in order to make a meaningful use of the forecast data. And remember you must pair forecasts and hindcasts up by using the same "system" for both of them.

06. Month

Select the month of the initialization date of the model run(s) you are interested in.
Note that in the current setup all monthly products are encoded using as nominal start date the 1st of each month, regardless of the real initialization date. You can find more information about how nominal start dates are assigned in the "Documentation" tab.

07. Leadtime month

Select the lead time(s) you are interested in. This is the time, in months, from the initialization date.
Note that the convention used for labelling the data implies that leadtime_month=1 is the first complete calendar month after the initialization date. In the current setup of all datasets that means that for a forecast initialised on the 1st of November, leadtime_month=1 is November.

08. Geographical area

You can select a global field ("whole available area") or a regional subselection by providing the latitude and longitude of its corners.

09. Data format

You can select the data format for your data retrieval.
Currently, GRIB format is used to store C3S seasonal forecast datasets data files.
An experimental netCDF conversion can be also accessed. You can find some related information in the "Documentation" tab.

10. Terms of use

You must accept the terms and conditions of the Copernicus User Licence in order to access the C3S seasonal forecast data.

01. Originating centre

Select the name of the institution the forecasting system of your interest originates from.

02. System

Select the version of the forecasting system. This is a numeric label and the available values are different for the different "originating centres". Note that for a given start date you could find more than one system available for a single "originating centre".
Please note that you must pair up your forecasts with the relevant hindcasts by using the same "system" for both of them. A full description of the use of the system keyword is available from the "Documentation" tab.

03. Variable

Select the parameter(s) you are interested in.

04. Pressure level

Select the pressure level(s) for the variables you are interested in.

05. Product type

Select the monthly product you are interested in.
Note that the products under the category "Individual members" consist of all available individual ensemble members, while those in the category "Ensemble" have a single value for each forecast system ensemble.

06. Year

Select the year of the initialization date of the model run(s) you are interested in.
Note that years in both the hindcast period and real-time forecasts are shown here together. You can find more details about hindcast and forecast years availability in the Start dates available in the CDS per forecast system page.

Please note that you must use the hindcast data in order to make a meaningful use of the forecast data. And remember you must pair forecasts and hindcasts up by using the same "system" for both of them.

07. Month

Select the month of the initialization date of the model run(s) you are interested in.
Note that in the current setup all monthly products are encoded using as nominal start date the 1st of each month, regardless of the real initialization date. You can find more information about how nominal start dates are assigned in the "Documentation" tab.

08. Leadtime month

Select the lead time(s) you are interested in. This is the time, in months, from the initialization date.
Note that the convention used for labelling the data implies that leadtime_month=1 is the first complete calendar month after the initialization date. In the current setup of all datasets that means that for a forecast initialised on the 1st of November, leadtime_month=1 is November.

09. Geographical area

You can select a global field ("whole available area") or a regional subselection by providing the latitude and longitude of its corners.

10. Data format

You can select the data format for your data retrieval.
Currently, GRIB format is used to store C3S seasonal forecast datasets data files.
An experimental netCDF conversion can be also accessed. You can find some related information in the "Documentation" tab.

11. Terms of use

You must accept the terms and conditions of the Copernicus User Licence in order to access the C3S seasonal forecast data.

Outputs from the ocean component of the forecasting systems

You will find one CDS catalogue entry for monthly averages of ocean variables available for all initialization dates (both hindcasts and real-time forecasts).

01. Originating centre

Select the name of the institution the forecasting system of your interest originates from.

02. System

Select the version of the forecasting system. This is a numeric label and the available values are different for the different "originating centres". Note that for a given start date you could find more than one system available for a single "originating centre".
Please note that you must pair up your forecasts with the relevant hindcasts by using the same "system" for both of them. A full description of the use of the system keyword is available from the "Documentation" tab.

03. Variable

Select the parameter(s) you are interested in.

04. Forecast type

Select the type of the forecast you are interested in from real-time forecasts ("forecast") or retrospective forecasts ("hindcast").

Please note that you must use the hindcast data in order to make a meaningful use of the forecast data. And remember you must pair forecasts and hindcasts up by using the same "system" for both of them.

05. Year

Select the year of the initialization date of the model run(s) you are interested in.

06. Month

Select the month of the initialization date of the model run(s) you are interested in.
Note that in the current setup all monthly products are encoded using as nominal start date the 1st of each month, regardless of the real initialization date. You can find more information about how nominal start dates are assigned in the "Documentation" tab.

07. Terms of use

You must accept the terms and conditions of the Copernicus User Licence in order to access the C3S seasonal forecast data.

Post-processed data

You will find two CDS catalogue entries for real-time forecast monthly anomalies; each contains the anomalies for the ensemble mean for each system and the individual ensemble members.
Anomalies are just available for real-time forecasts start dates (from 2017 onwards).

One dataset contains surface (or single level) parameters, the other contains variables on 11 pressure levels spanning 925 hPa to 10 hPa.


01. Originating centre

Select the name of the institution the forecasting system of your interest originates from.

02. System

Select the version of the forecasting system. This is a numeric label and the available values are different for the different "originating centres".
A full description of the use of the system keyword is available from the "Documentation" tab.

03. Variable

Select the parameter(s) you are interested in.

04. Product type

Select the monthly product you are interested in.
Note that the products under the category "Individual members" consist of all available individual ensemble members, while those in the category "Ensemble" have a single value for each forecast system ensemble.

05. Year

Select the year of the initialization date of the model run(s) you are interested in.
Note that anomalies are just available for real-time forecasts start dates.

06. Month

Select the month of the initialization date of the model run(s) you are interested in.
Note that in the current setup all monthly products are encoded using as nominal start date the 1st of each month, regardless of the real initialization date. You can find more information about how nominal start dates are assigned in the "Documentation" tab.

07. Leadtime month

Select the lead time(s) you are interested in. This is the time, in months, from the initialization date.
Note that the convention used for labelling the data implies that leadtime_month=1 is the first complete calendar month after the initialization date. In the current setup of all datasets that means that for a forecast initialised on the 1st of November, leadtime_month=1 is November.

08. Geographical area

You can select a global field ("whole available area") or a regional subselection by providing the latitude and longitude of its corners.

09. Data format

You can select the data format for your data retrieval.
Currently, GRIB format is used to store C3S seasonal forecast datasets data files.
An experimental netCDF conversion can be also accessed. You can find some related information in the "Documentation" tab.

10. Terms of use

You must accept the terms and conditions of the Copernicus User Licence in order to access the C3S seasonal forecast data.

01. Originating centre

Select the name of the institution the forecasting system of your interest originates from.

02. System

Select the version of the forecasting system. This is a numeric label and the available values are different for the different "originating centres".
A full description of the use of the system keyword is available from the "Documentation" tab.

03. Variable

Select the parameter(s) you are interested in.

04. Pressure level

Select the pressure level(s) for the variables you are interested in.

05. Product type

Select the monthly product you are interested in.
Note that the products under the category "Individual members" consist of all available individual ensemble members, while those in the category "Ensemble" have a single value for each forecast system ensemble.

06. Year

Select the year of the initialization date of the model run(s) you are interested in.
Note that anomalies are just available for real-time forecasts start dates.

07. Month

Select the month of the initialization date of the model run(s) you are interested in.
Note that in the current setup all monthly products are encoded using as nominal start date the 1st of each month, regardless of the real initialization date. You can find more information about how nominal start dates are assigned in the "Documentation" tab.

08. Leadtime month

Select the lead time(s) you are interested in. This is the time, in months, from the initialization date.
Note that the convention used for labelling the data implies that leadtime_month=1 is the first complete calendar month after the initialization date. In the current setup of all datasets that means that for a forecast initialised on the 1st of November, leadtime_month=1 is November.

09. Geographical area

You can select a global field ("whole available area") or a regional subselection by providing the latitude and longitude of its corners.

10. Data format

You can select the data format for your data retrieval.
Currently, GRIB format is used to store C3S seasonal forecast datasets data files.
An experimental netCDF conversion can be also accessed. You can find some related information in the "Documentation" tab.

11. Terms of use

You must accept the terms and conditions of the Copernicus User Licence in order to access the C3S seasonal forecast data.

This document has been produced in the context of the Copernicus Climate Change Service (C3S).

The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of C3S on behalf of the European Union (Delegation agreement signed on 11/11/2014). All information in this document is provided "as is" and no guarantee or warranty is given that the information is fit for any particular purpose.

The users thereof use the information at their sole risk and liability. For the avoidance of all doubt, the European Commission and the European Centre for Medium-Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view.

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