Visualize the HadCRUT5 temperature datasets

HadCRUT5 is a gridded dataset of global historical surface temperature anomalies relative to a 1961-1990 reference period. Data are available for each month from January 1850 onwards, on a 5 degree grid and as global and regional average time series. The dataset is a collaborative product of the Met Office Hadley Centre and the Climatic Research Unit at the University of East Anglia.

The current version of HadCRUT5 is HadCRUT.5.0.2.0, available from the download page.

— source: HadCRUT5 Index

A detailed description of the datasets can be found in the Answers to Frequently Asked Questions.

List of the datafiles that are loaded by the Python script: * HadCRUT.5.0.2.0.analysis.summary_series.global.annual.nc * HadCRUT.5.0.2.0.analysis.summary_series.northern_hemisphere.annual.nc * HadCRUT.5.0.2.0.analysis.summary_series.southern_hemisphere.annual.nc

HadCRUT5 data are downloaded from: https://www.metoffice.gov.uk/hadobs/hadcrut5/data/HadCRUT.5.0.2.0/download.html

Plot of the temperature anomalies

The following plots have been generated by the Python scripts hadcrut5_plot.py and hadcrut5_bars.py. They require the Python libraries: Matplotlib, netCDF4, NumPy, and Requests.

If Python and the required libraries are not installed on your system, you can simply install uv and run the commands listed below prefixed with uv run. For example uv run ./hadcrut5_plot.py.

hadcrut5_plot.py — Script usage

``` $ ./hadcrut5plot.py --help usage: hadcrut5plot.py [-h] [-f OUTFILE] [-p PERIOD] [-m SMOOTHER] [-g] [-n] [-s] [-a ANNOTATE] [-v]

Parse and plot the HadCRUT5 temperature datasets v2024.1 (stable) Copyright (C) 2020-2025 Davide Madrisan d.madrisan@proton.me License: GNU General Public License v3.0

options: -h, --help show this help message and exit -a ANNOTATE, --annotate ANNOTATE add temperature annotations (0: no annotations, 1 (default): bottom only, 2: all ones -f OUTFILE, --outfile OUTFILE name of the output PNG file -g, --global plot the Global Temperatures -m SMOOTHER, --smoother SMOOTHER make the lines smoother by using N-year means -n, --northern Northern Hemisphere Temperatures -p PERIOD, --period PERIOD show anomalies related to 1961-1990 (default), 1850-1900, or 1880-1920 -s, --southern Southern Hemisphere Temperatures -t TIMESERIES, --time-series TIMESERIES do plot the "annual" time series (default) or the "monthly" one -v, --verbose make the operation more talkative

examples: hadcrut5plot.py hadcrut5plot.py --global --annotate=2 hadcrut5plot.py --period "1850-1900" hadcrut5plot.py --period "1850-1900" --smoother 5 hadcrut5plot.py --period "1880-1920" --outfile HadCRUT5-1880-1920.png hadcrut5plot.py --period "1880-1920" --time-series monthly --global ```

hadcrut5_plot.py select the period 1961-90 by default but supports (see the command-line switch--period) two other base periods found in the literature: 1850-1900, and 1880-1920.

$ ./hadcrut5_plot.py --annotate=2 --outfile plots/HadCRUT5-1961-1990.png

$ ./hadcrut5_plot.py --annotate=2 --period "1850-1900" --outfile plots/HadCRUT5-1850-1900.png

$ ./hadcrut5_plot.py --annotate=2 --period "1880-1920" --outfile plots/HadCRUT5-1880-1920.png

Plots using the N-year mean data

By adding the command-line option --smoother N you can create the same three plots, but using the N-year means data. For instance --smoother 5 will get you a better idea of the trend lines.

Image generated for the anomalies related to the period 1880-1920. $ ./hadcrut5_plot.py --period "1880-1920" --smoother 5 --outfile plots/HadCRUT5-1880-1920-smoother.png

Plots using the monthly mean data

The command-line option --time-series monthly selects the monthly HadCRUT5 datasets (by default the dataset providing the annual means is selected).

Image displying the monthly anomalies related to the period 1880-1920, for the global temperatures only. $ ./hadcrut5_plot.py --global --period "1880-1920" --time-series monthly

hadcrut5_bars.py — Script usage

``` usage: hadcrut5_bars.py [-h] [-f OUTFILE] [-p PERIOD] [-v]

Parse and plot the HadCRUT5 temperature datasets v2024.1 (stable) Copyright (C) 2020-2025 Davide Madrisan d.madrisan@proton.me License: GNU General Public License v3.0

options: -h, --help show this help message and exit -f OUTFILE, --outfile OUTFILE name of the output PNG file -p PERIOD, --period PERIOD show anomalies related to 1961-1990 (default), 1850-1900, or 1880-1920 -v, --verbose make the operation more talkative

examples: hadcrut5bars.py hadcrut5bars.py --period "1850-1900" hadcrut5bars.py --period "1880-1920" hadcrut5bars.py --outfile HadCRUT5-global.png The image for to the anomalies related to the period `1880-1920` follows. $ ./hadcrut5_bars.py --period "1880-1920" --outfile plots/HadCRUT5-global-1880-1920.png ```

hadcrut5_stripe.py — Script usage

``` usage: hadcrut5_stripe.py [-h] [-f OUTFILE] [-r {global,northern,southern}] [-v] [-l]

Parse and plot a stripe image of the HadCRUT5 temperature datasets v2024.1 (stable) Copyright (C) 2020-2025 Davide Madrisan d.madrisan@proton.me License: GNU General Public License v3.0

options: -h, --help show this help message and exit -f OUTFILE, --outfile OUTFILE name of the output PNG file -r {global,northern,southern}, --region {global,northern,southern} select between Global (default), Northern, or Southern Temperatures -v, --verbose make the operation more talkative -l, --no-labels do not disply the header and footer labels

examples: hadcrut5stripe.py hadcrut5stripe.py --no-labels --region northern hadcrut5_stripe.py --region global --outfile HadCRUT5-stripe-global.png ```

Below is a generated striped image for global anomalies. $ ./hadcrut5_stripe.py --region global

License

The Python code of this project is released under the GPL-3.0 license. The graphics have a CC-BY4.0 license, so can be used for any purpose as long as credit is given to Madrisan Davide and a link is provided to this website.