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.

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.

Release Branch

Once the features intended for the release are on master, 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, 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.


The documentation should include all of the what’s new 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 are to change the version string in the source of and include the release date in the relevant what’s new 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.

Conda Recipe

Once a release is cut, the Iris feedstock for the conda recipe must be updated to build the latest release of Iris and push this artefact to conda forge.

Merge Back

After the release is cut, the changes shall be merged back onto the Scitools/iris master branch.

To achieve this, first cut a local branch from the release branch, {release}.x. Next add a commit changing the release string to match the release string on scitools/master. This branch can now be proposed as a pull request to master. This work flow ensures that the commit identifiers are consistent between the .x branch and master.

Point Releases

Bug fixes may be implemented and targeted as the .x branch. These should lead to a new point release, another tag. For example, a fix for a problem with 1.9.0 will be merged into 1.9.x, and then released by tagging 1.9.1.

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 master.

Maintainer Steps

These steps assume a release for v1.9 is to be created

Release Steps

  1. Create the branch 1.9.x on the main repo, not in a forked repo, for the release candidate or release. The only exception is for a point/bugfix release as it should already exist

  2. Update the what’s new for the release:

    • Copy docs/iris/src/whatsnew/latest.rst to a file named v1.9.rst

    • Delete the docs/iris/src/whatsnew/latest.rst file so it will not cause an issue in the build

    • In v1.9.rst update the page title (first line of the file) to show the date and version in the format of v1.9 (DD MMM YYYY). For example v1.9 (03 Aug 2020)

    • Review the file for correctness

    • Work with the development team to create a ‘highlights’ section at the top of the file, providing extra detail on notable changes

    • Add v1.9.rst to git and commit all changes, including removal of latest.rst

  3. Update the what’s new index docs/iris/src/whatsnew/index.rst

    • Temporarily remove reference to latest.rst

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

  4. Update the version string, to 1.9.0

  5. Check your changes by building the documentation and viewing the changes

  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 master. 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. Copy docs/iris/src/whatsnew/latest.rst.template to docs/iris/src/whatsnew/latest.rst. This will reset the file with the unreleased heading and placeholders for the what’s new headings

  3. Add back in the reference to latest.rst to the what’s new index docs/iris/src/whatsnew/index.rst

  4. Update version string to show as 1.10.dev0

  5. Merge back to master