All ERA5 datasets have been migrated to Zarr v3 with improved chunking. Previous dataset versions are still available, but we recommend using the new ones.
Future updates will only apply to Zarr v3 datasets, including ERA5 monthly updates.

ERA5 monthly anomalies of Essential Climate Variables

This dataset is a curated subset of monthly anomalies for Essential Climate Variables (ECVs) derived from ECMWF's Essential Climate Variables for assessment of climate variability from 1979 to present.

The data are available from 1978-01-01 to 2025-05-01. They are distributed as a Zarr ARCO archive optimized for regional and timeseries analysis.

⚠️ Warning: The monthly updates to this dataset have been discontinued.

If you require up-to-date anomaly calculations, you can compute them using the ERA5 Single Levels Monthly Means dataset available on Earth Data Hub.

Example Code


# Choose one of the methods below to open the dataset
# Aassign it to a variable named `era5_monthly`

# Extract the 2 metre temperaute
t2m = era5_monthly.t2m

# Compute the monthly climatology (1991-2020) in one chained step
t2m_1991_2020_clima = (
    t2m.sel(valid_time=slice("1991", "2020"))
    .groupby("valid_time.month")
    .mean()
)

# Compute the anomalies
t2m_anomaly = (t2m.groupby("valid_time.month") - t2m_1991_2020_clima)

# Optional: load the data into memory
t2m_anomaly.load()

How to download the data

The default (and preferred) way to access the data requires accessing the api.earthdatahub.destine.eu domain and a valid API key.

Method 1: quick access

It is possible to include the token directly in the URL.

1import xarray as xr
2
3xr.open_dataset(
4    "https://edh:<your personal access token>@api.earthdatahub.destine.eu/more-era5/ecv-for-climate-change-1981-2010-anomaly-v0",
5    chunks={},
6    engine="zarr",
7)

Method 2: advanced access

The Python snippet gather the token from a netrc file.

It's required to before running the code snippet below.
1import xarray as xr
2
3xr.open_dataset(
4    "https://api.earthdatahub.destine.eu/more-era5/ecv-for-climate-change-1981-2010-anomaly-v0",
5    storage_options={"client_kwargs":{"trust_env":True}},
6    chunks={},
7    engine="zarr",
8)

Variables

Short NameUnitsDescription
r
%

Relative humidity

siconc
(0 - 1)

Sea ice area fraction

t2m
K

2 metre temperature

tp
m

Total precipitation

DestinE platform