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A release of Iris is a tag on the SciTools/Iris Github repository.

The summary below is of the main areas that constitute the release. The final section details the Maintainer Steps to take.

Release Manager#

A Release Manager will be nominated for each release of Iris. This role involves:

  • deciding which features and bug fixes should be included in the release

  • managing the project board for the release

  • using GitHub Discussion releases category for documenting intent and capturing any discussion about the release

The Release Manager will make the release, ensuring that all the steps outlined on this page are completed.

Before Release#


Ensure that any behaviour which has been deprecated for the correct number of previous releases is now finally changed. More detail, including the correct number of releases, is in Deprecations.

Standard Names#

Update the file etc/cf-standard-name-table.xml to the latest CF standard names, from the latest CF standard names. ( This is used during build to automatically generate the sourcefile lib/iris/ )

Release Branch#

Once the features intended for the release are on main, a release branch should be created, in the SciTools/iris repository. This will have the name:

v{major release number}.{minor release number}.x

for example:


This branch shall be used to finalise the release details in preparation for the release candidate.

Release Candidate#

Prior to a release, a release candidate tag may be created, marked as a pre-release in GitHub, with a tag ending with rc followed by a number (0-based), e.g.,:


If created, the pre-release shall be available for a minimum of two weeks prior to the release being cut. However a 4 week period should be the goal to allow user groups to be notified of the existence of the pre-release and encouraged to test the functionality.

A pre-release is expected for a major or minor release, but not for a point release.

If new features are required for a release after a release candidate has been cut, a new pre-release shall be issued first.

Make the release candidate available as a conda package on the conda-forge Anaconda channel using the rc_iris label. To do this visit the conda-forge iris-feedstock and follow CFEP-05. For further information see the conda-forge User Documentation.


The documentation should include all of the whatsnew entries for the release. This content should be reviewed and adapted as required.

Steps to achieve this can be found in the Maintainer Steps.

The Release#

The final steps of the release are to change the version string __version__ in the source of and ensure the release date and details are correct in the relevant whatsnew page within the documentation.

Once all checks are complete, the release is cut by the creation of a new tag in the SciTools/iris repository.

Update conda-forge#

Once a release is cut on GitHub, update the Iris conda recipe on the conda-forge iris-feedstock for the release. This will build and publish the conda package on the conda-forge Anaconda channel.

Update PyPI#

Update the scitools-iris project on PyPI with the latest Iris release.

To do this perform the following steps.

Create a conda environment with the appropriate conda packages to build the source distribution (sdist) and pure Python wheel (bdist_wheel):

> conda create -n iris-pypi -c conda-forge --yes pip python setuptools twine wheel
> . activate iris-pypi

Checkout the appropriate Iris <release> tag from the appropriate <repo>. For example, to checkout tag v1.0 from upstream:

> git fetch upstream --tags
> git checkout v1.0

Build the source distribution and wheel from the Iris root directory:

> python sdist bdist_wheel

This ./dist directory should now be populated with the source archive .tar.gz file, and built distribution .whl file.

Check that the package description will render properly on PyPI for each of the built artifacts:

> python -m twine check dist/*

To list and check the contents of the binary wheel:

> python -m zipfile --list dist/*.whl

If all seems well, sufficient maintainer privileges will be required to upload these artifacts to scitools-iris on PyPI:

> python -m twine upload --repository-url dist/*

Ensure that the artifacts are successfully uploaded and available on scitools-iris before creating a conda test environment to install Iris from PyPI:

> conda deactivate
> conda env create --file ./requrements/ci/iris.yml
> . activate iris-dev
> conda install -c conda-forge pip
> python -m pip install --no-deps scitools-iris

For further details on how to test Iris, see Running the Tests.

See also

For further information on packaging and uploading a project to PyPI, please refer to Generating Distribution Archives and Packaging Your Project.

Merge Back#

After the release is cut, the changes from the release branch should be merged back onto the SciTools/iris main branch.

To achieve this, first cut a local branch from the latest main branch, and git merge the .x release branch into it. Ensure that the iris.__version__, docs/src/whatsnew/index.rst, and docs/src/whatsnew/latest.rst are correct, before committing these changes and then proposing a pull-request on the main branch of SciTools/iris.

Point Releases#

Bug fixes may be implemented and targeted on the .x release branch. These should lead to a new point release, and another tag. For example, a fix for a problem with the v1.9.0 release will be merged into v1.9.x release branch, and then released by tagging v1.9.1.

New features shall not be included in a point release, these are for bug fixes.

A point release does not require a release candidate, but the rest of the release process is to be followed, including the merge back of changes into main.

Maintainer Steps#

These steps assume a release for 1.9.0 is to be created.

Release Steps#

  1. Create the release feature branch v1.9.x on SciTools/iris. The only exception is for a point/bugfix release, as it should already exist

  2. Update the version string e.g., to 1.9.0

  3. Update the whatsnew for the release:

    • Use git to rename docs/src/whatsnew/latest.rst to the release version file v1.9.rst

    • Use git to delete the docs/src/whatsnew/latest.rst.template file

    • In v1.9.rst remove the [unreleased] caption from the page title. Note that, the Iris version and release date are updated automatically when the documentation is built

    • Review the file for correctness

    • Work with the development team to populate the Release Highlights dropdown at the top of the file, which provides extra detail on notable changes

    • Use git to add and commit all changes, including removal of latest.rst.template.

  4. Update the whatsnew index docs/src/whatsnew/index.rst

    • Remove the reference to latest.rst

    • Add a reference to v1.9.rst to the top of the list

  5. Check your changes by building the documentation and reviewing

  6. Once all the above steps are complete, the release is cut, using the Draft a new release button on the Iris release page

Post Release Steps#

  1. Check the documentation has built on Read The Docs. The build is triggered by any commit to main. Additionally check that the versions available in the pop out menu in the bottom left corner include the new release version. If it is not present you will need to configure the versions available in the admin dashboard in Read The Docs.

  2. Review the Active Versions for the scitools-iris project on Read The Docs to ensure that the appropriate versions are Active and/or Hidden. To do this Edit the appropriate version e.g., see Editing v3.0.0rc0 (must be logged into Read the Docs).

  3. Merge back to main