Drop Python 3.9 support and bump GHA actions to Node.js 24

.github/workflows/python-publish.yml

@@ -16,7 +16,7 @@ jobs:
       contents: write
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
         with:
           persist-credentials: false
       - name: Create Release
@@ -34,11 +34,11 @@ jobs:
     needs: release
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           persist-credentials: false
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: "3.x"
       - name: Install dependencies

.github/workflows/upstream-dev-ci.yml

@@ -26,7 +26,7 @@ jobs:
     outputs:
       triggered: ${{ steps.detect-trigger.outputs.trigger-found }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           fetch-depth: 2
           persist-credentials: false
@@ -56,12 +56,12 @@ jobs:
     outputs:
       artifacts_availability: ${{ steps.status.outputs.ARTIFACTS_AVAILABLE }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           fetch-depth: 0 # Fetch all history for all branches and tags.
           persist-credentials: false
       - name: setup conda (micromamba)
-        uses: mamba-org/setup-micromamba@v2
+        uses: mamba-org/setup-micromamba@v3
         with:
           cache-downloads: true
           cache-environment: true
@@ -90,15 +90,15 @@ jobs:
         run: |
           set -euo pipefail
           python -m pytest --timeout=60 -rf | tee output-${{ matrix.python-version }}-log || (
-              echo '::set-output name=ARTIFACTS_AVAILABLE::true' && false
+              echo "ARTIFACTS_AVAILABLE=true" >> "$GITHUB_OUTPUT" && false
           )
       - name: Upload artifacts
         if: |
           failure()
           && steps.status.outcome == 'failure'
           && github.event_name == 'schedule'
           && github.repository == 'xarray-contrib/xskillscore'
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: output-${{ matrix.python-version }}-log
           path: output-${{ matrix.python-version }}-log
@@ -119,13 +119,13 @@ jobs:
       run:
         shell: bash
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: "3.x"
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@v7
         with:
           path: /tmp/workspace/logs
       - name: Move all log files into a single directory
@@ -138,7 +138,7 @@ jobs:
           wget https://raw.githubusercontent.com/pydata/xarray/master/.github/workflows/parse_logs.py
           python parse_logs.py logs/**/*-log
       - name: Report failures
-        uses: actions/github-script@v7
+        uses: actions/github-script@v8
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           script: |

.github/workflows/xskillscore_installs.yml

@@ -17,7 +17,7 @@ jobs:
     outputs:
       triggered: ${{ steps.detect-trigger.outputs.trigger-found }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           fetch-depth: 2
           persist-credentials: false
@@ -37,13 +37,13 @@ jobs:
     strategy:
       matrix:
         os: [ "ubuntu-latest", "macos-latest", "windows-latest" ]
-        python-version: [ "3.9" ]
+        python-version: [ "3.10" ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           persist-credentials: false
       - name: Setup python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: "${{ matrix.python-version }}"
       - name: Install dependencies

.github/workflows/xskillscore_testing.yml

@@ -18,7 +18,7 @@ jobs:
     outputs:
       triggered: ${{ steps.detect-trigger.outputs.trigger-found }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           fetch-depth: 2
           persist-credentials: false
@@ -38,23 +38,19 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [ "3.9", "3.10", "3.11", "3.12", "3.13" ]
+        python-version: [ "3.10", "3.11", "3.12", "3.13" ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           persist-credentials: false
       - name: Set up conda (micromamba)
-        uses: mamba-org/setup-micromamba@v2
+        uses: mamba-org/setup-micromamba@v3
         with:
           cache-downloads: true
           cache-environment: true
           environment-file: ci/minimum-tests.yml
           create-args: >
             python=${{ matrix.python-version }}
-      - name: Install minimal numpy
-        if: matrix.python-version == '3.9'
-        run: |
-          micromamba install numpy==1.24
       - name: Run tests
         run: |
           pytest -n auto --cov=xskillscore --cov-report=xml --verbose
@@ -78,11 +74,11 @@ jobs:
       matrix:
         python-version: [ "3.13" ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           persist-credentials: false
       - name: Set up conda (micromamba)
-        uses: mamba-org/setup-micromamba@v2
+        uses: mamba-org/setup-micromamba@v3
         with:
           cache-downloads: true
           cache-environment: true
@@ -106,13 +102,13 @@ jobs:
         shell: bash -l {0}
     strategy:
       matrix:
-        python-version: [ "3.9" ]
+        python-version: [ "3.10" ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           persist-credentials: false
       - name: Set up conda (micromamba)
-        uses: mamba-org/setup-micromamba@v2
+        uses: mamba-org/setup-micromamba@v3
         with:
           cache-downloads: true
           cache-environment: true

CHANGELOG.rst

@@ -3,6 +3,23 @@ Changelog History
 =================
 
 
+xskillscore vNext (unreleased)
+------------------------------
+
+Breaking Changes
+~~~~~~~~~~~~~~~~
+- Dropped support for Python 3.9. The minimum supported version is now Python 3.10.
+  `Aaron Spring`_
+
+Internal Changes
+~~~~~~~~~~~~~~~~
+- Bumped GitHub Actions to versions running on Node.js 24 (``actions/checkout@v5``,
+  ``actions/setup-python@v6``, ``actions/upload-artifact@v6``,
+  ``actions/download-artifact@v7``, ``actions/github-script@v8``,
+  ``mamba-org/setup-micromamba@v3``) to silence Node.js 20 deprecation warnings.
+  `Aaron Spring`_
+
+
 xskillscore v0.0.29 (2026-02-18)
 --------------------------------
 

ci/dev.yml

@@ -2,7 +2,7 @@ name: xskillscore-dev
 channels:
   - conda-forge
 dependencies:
-  - python >= 3.9,<3.14
+  - python >= 3.10,<3.14
   - pip >= 23.0
   # Documentation
   - matplotlib-base

ci/doc.yml

@@ -2,7 +2,7 @@ name: xskillscore-docs
 channels:
   - conda-forge
 dependencies:
-  - python >=3.9,<3.14
+  - python >=3.10,<3.14
   - pip >=23.0
   - bottleneck
   - cftime

ci/docs_notebooks.yml

@@ -3,7 +3,7 @@ channels:
   - conda-forge
   - nodefaults
 dependencies:
-  - python >=3.9,<3.14
+  - python >=3.10,<3.14
   - pip >=23.0
   - bottleneck
   - cftime

ci/minimum-tests.yml

@@ -2,7 +2,7 @@ name: xskillscore-minimum-tests
 channels:
   - conda-forge
 dependencies:
-  - python >=3.9,<3.14
+  - python >=3.10,<3.14
   - pip >=23.0
   - bottleneck
   - cftime

pyproject.toml

@@ -22,15 +22,14 @@ classifiers = [
     "Natural Language :: English",
     "Operating System :: OS Independent",
     "Programming Language :: Python :: 3 :: Only",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
     "Topic :: Scientific/Engineering :: Atmospheric Science",
     "Topic :: Scientific/Engineering :: Mathematics",
 ]
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 license = {file = "LICENSE.txt"}
 dynamic = ["readme", "version"]
 
@@ -112,5 +111,5 @@ ignore_missing_imports = true
 follow_imports = "silent"
 
 [tool.black]
-target-version = ["py39", "py310", "py311", "py312", "py313"]
+target-version = ["py310", "py311", "py312", "py313"]
 line-length = 100