diff --git a/.github/workflows/build_workflow.yml b/.github/workflows/build_workflow.yml
index 198a9b4c5..c5ffdad71 100644
--- a/.github/workflows/build_workflow.yml
+++ b/.github/workflows/build_workflow.yml
@@ -27,7 +27,8 @@ jobs:
         shell: bash -l {0}
     strategy:
       matrix:
-        python-version: ["3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
+      fail-fast: false
     steps:
       - id: skip_check
         uses: fkirc/skip-duplicate-actions@master
@@ -48,7 +49,7 @@ jobs:
           path: ~/conda_pkgs_dir
           key:
             ${{ runner.os }}-${{ matrix.python-version }}-conda-${{ env.CACHE_NUMBER }}-${{
-            hashFiles('dev-spec.txt,setup.py') }}
+            hashFiles('dev-spec.txt,pyproject.toml') }}
 
       - if: ${{ steps.skip_check.outputs.should_skip != 'true' }}
         name: Set up Conda Environment
diff --git a/.github/workflows/docs_workflow.yml b/.github/workflows/docs_workflow.yml
index d11d3f4b1..e0b5aee6f 100644
--- a/.github/workflows/docs_workflow.yml
+++ b/.github/workflows/docs_workflow.yml
@@ -9,6 +9,9 @@ on:
   release:
     types: [published]
 
+env:
+  PYTHON_VERSION: "3.10"
+
 jobs:
   publish-docs:
     runs-on: ubuntu-latest
@@ -41,14 +44,14 @@ jobs:
           channels: conda-forge
           channel-priority: strict
           auto-update-conda: true
-          python-version: ${{ matrix.python-version }}
+          python-version: ${{ env.PYTHON_VERSION }}
 
       - if: ${{ steps.skip_check.outputs.should_skip != 'true' }}
         name: Install mpas_analysis
         run: |
           git config --global url."https://github.com/".insteadOf "git@github.com:"
           conda create -n mpas_analysis_dev --file dev-spec.txt \
-            python=${{ matrix.python-version }}
+            python=${{ env.PYTHON_VERSION }}
           conda activate mpas_analysis_dev
           python -m pip install -vv --no-deps --no-build-isolation -e .
 
diff --git a/ci/python3.9.yaml b/ci/python3.9.yaml
new file mode 100644
index 000000000..7929b1920
--- /dev/null
+++ b/ci/python3.9.yaml
@@ -0,0 +1,8 @@
+channel_sources:
+- conda-forge,defaults
+pin_run_as_build:
+  python:
+    min_pin: x.x
+    max_pin: x.x
+python:
+- 3.9.* *_cpython
diff --git a/pyproject.toml b/pyproject.toml
index 1d8d4ac04..56bd7ef34 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -66,21 +66,6 @@ dependencies = [
     "xarray>=0.14.1"
 ]
 
-[tool.isort]
-multi_line_output = "3"
-include_trailing_comma = true
-force_grid_wrap = "0"
-use_parentheses = true
-line_length = "79"
-
-[tool.mypy]
-python_version = "3.10"
-check_untyped_defs = true
-ignore_missing_imports = true
-warn_unused_ignores = true
-warn_redundant_casts = true
-warn_unused_configs = true
-
 [build-system]
 requires = ["setuptools>=60"]
 build-backend = "setuptools.build_meta"