Python 3.15.0 Added to GitHub Actions python-versions

Python 3.15.0 Now Available in GitHub Actions

Python 3.15.0 has been added to the actions/python-versions repository, enabling developers to test their code against the newest stable Python release directly from GitHub Actions workflows. With this update, teams can simply add "3.15" to their testing matrix and run CI jobs against Python 3.15.0.

The addition was announced by Simon Willison in a link post published on his weblog on 10th October 2026. While he described the news as a niche update, it is a significant step for projects that want to ensure compatibility with the latest Python version through continuous integration.

An Hourly Watch, Automated by ChatGPT

Willison revealed that he had been waiting for the release for a couple of days. In an unusual move, he instructed ChatGPT to check for the update automatically: clone the actions/python-versions repository from GitHub and run git pull once an hour until the stable 3.15 version appeared, then notify him about it.

This small automation highlights how developers increasingly delegate routine monitoring tasks to AI assistants. Once the version landed, the hourly checks paid off and Willison could immediately share the news with his readers.

What This Means for Python Projects

For maintainers of Python packages and applications, the update means official GitHub Actions support for testing against Python 3.15.0 is now available. Projects that pin their CI to supported Python versions can add 3.15 to their matrix and verify compatibility with the release without waiting for third party runners or custom setup steps.

The release continues the pattern of the actions/python-versions repository tracking stable Python releases, making it easier for the open source community to adopt new versions as they ship.

Sources: Simonwillison