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()