ERA5¶

ECMWF Reanalysis v5

Available

At a glance¶

Note on period: Initial-release data (ERA5T) are available about 5 days behind real time; the final ERA5 data replace them two to three months later and may, in rare cases, differ from ERA5T.

Overview¶

ERA5 is the fifth-generation ECMWF reanalysis for the global climate and weather, produced for the Copernicus Climate Change Service (C3S) and replacing ERA-Interim. It provides hourly estimates of a large number of atmospheric, ocean-wave and land-surface quantities from 1940 onwards. The data on the CDS are a regridded subset of the full dataset at native resolution, on a regular 0.25° latitude-longitude grid.

What changes with the successor¶

ERA5 → ERA6 Planned¶

Next-generation reanalysis in production since 2026, at 14 km horizontal resolution with an ocean component; the first production streams, covering 2007 onwards, are expected towards the end of 2027, and ERA6 will replace ERA5T once sufficient data have been published.

Sources: ECMWF Newsletter 188 (2026) — ERA6 reanalysis is in production · Copernicus — Copernicus Climate's ERA6 reanalysis production starts (2026-03-06) · Hersbach et al. (2020), The ERA5 global reanalysis, QJRMS

Compare the two side by side

Available variables¶

Key parameters from the ERA5 data documentation (parameter listings) and the ECMWF parameter database. Names are GRIB short names. NetCDF files from the CDS mostly keep them, but a few are renamed (2t→t2m, 10u→u10, etc.). Accumulated and flux parameters (precipitation, radiation, heat fluxes) are time integrals, so check the units.

instantaneous mean accumulated maximum minimum static — instantaneous: value at the time stamp · mean/accumulated/maximum/minimum: over the indicated interval · static: does not change with time

Surface and single levels (instantaneous)¶

Surface and single levels (accumulations and min/max, from forecasts)¶

Pressure levels (37 levels, 1000–1 hPa)¶

Ocean waves¶

Land and invariant fields¶

The full variable list is in the official documentation.

How to get the data¶

• Copernicus Climate Data Store (CDS) — single levels — Web download / CDS API (cdsapi)
  • Requires an ECMWF account. API requests fail until you have accepted the dataset's licence on its download page.
• Copernicus Climate Data Store (CDS) — pressure levels — Web download / CDS API (cdsapi)
• NSF NCAR GDEX (d633000, 0.25° mirror) — Web download / THREDDS
  • Requires an NCAR account. Updated monthly, so it lags the CDS by a few months; a good option for historical periods when the CDS queue is long.

Example code¶

Put the url (https://cds.climate.copernicus.eu/api) and your personal API key in ~/.cdsapirc before running.

# pip install --upgrade cdsapi
import cdsapi

client = cdsapi.Client()
client.retrieve(
    "reanalysis-era5-single-levels",
    {
        "product_type": ["reanalysis"],
        "variable": ["2m_temperature"],
        "year": ["2024"],
        "month": ["01"],
        "day": ["01"],
        "time": ["00:00", "12:00"],
        "data_format": "netcdf",
        "download_format": "unarchived",
    },
    "era5_t2m_20240101.nc",
)

Practical tips¶

• Old API keys and .cdsapirc URLs stopped working when the new CDS replaced the legacy one in September 2024. If an old script fails, check this first.
• The ERA5T period (roughly the last three months) can be overwritten by final ERA5 data, so record your download date for anything you publish.
• Cite the DOI of each CDS dataset you actually used (single levels, pressure levels, monthly means, etc.), not just one.

Notices and change history¶

References for your paper¶

Dataset citation¶

Hourly data on single levels — DOI 10.24381/cds.adbb2d47

@misc{era5_single_levels,
  author    = {Hersbach, H. and Bell, B. and Berrisford, P. and Biavati, G. and Hor{\'a}nyi, A. and Mu{\~n}oz Sabater, J. and Nicolas, J. and Peubey, C. and Radu, R. and Rozum, I. and Schepers, D. and Simmons, A. and Soci, C. and Dee, D. and Th{\'e}paut, J.-N.},
  title     = {{ERA5} hourly data on single levels from 1940 to present},
  year      = {2023},
  publisher = {Copernicus Climate Change Service (C3S) Climate Data Store (CDS)},
  doi       = {10.24381/cds.adbb2d47},
  note      = {Accessed on DD-MMM-YYYY}
}

Hourly data on pressure levels — DOI 10.24381/cds.bd0915c6

@misc{era5_pressure_levels,
  author    = {Hersbach, H. and Bell, B. and Berrisford, P. and Biavati, G. and Hor{\'a}nyi, A. and Mu{\~n}oz Sabater, J. and Nicolas, J. and Peubey, C. and Radu, R. and Rozum, I. and Schepers, D. and Simmons, A. and Soci, C. and Dee, D. and Th{\'e}paut, J.-N.},
  title     = {{ERA5} hourly data on pressure levels from 1940 to present},
  year      = {2023},
  publisher = {Copernicus Climate Change Service (C3S) Climate Data Store (CDS)},
  doi       = {10.24381/cds.bd0915c6},
  note      = {Accessed on DD-MMM-YYYY}
}

Reference papers¶

ERA5 reference paper — DOI 10.1002/qj.3803

@article{hersbach2020era5,
  author  = {Hersbach, Hans and Bell, Bill and Berrisford, Paul and others},
  title   = {The {ERA5} global reanalysis},
  journal = {Quarterly Journal of the Royal Meteorological Society},
  volume  = {146},
  number  = {730},
  pages   = {1999--2049},
  year    = {2020},
  doi     = {10.1002/qj.3803}
}

Acknowledgements¶

Acknowledge the use of C3S/ECMWF data and give the dataset DOI(s) above with your access date. For the exact recommended wording, see "Citation and attribution" on the CDS dataset page.

Information on the datasets used in this study was compiled with the help of the Korean Climate Data Navigator (KCDN) (Sim, 2026; https://doi.org/10.5281/zenodo.23300923).

Links¶

• CDS — ERA5 hourly data on single levels
• ECMWF Forum — Announcements
• NCAR Climate Data Guide — ERA5