diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 51e65229..93112d9b 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -33,8 +33,8 @@ jobs:
   test:
     needs: lint
     strategy:
-      matrix: #using macos-13, last available intel architecture. macos-latest is arm64 architecture.
-        os: [macos-13, windows-latest, ubuntu-latest, macos-latest]
+      matrix: #using macos-15-intel, last available intel architecture. macos-latest is arm64 architecture.
+        os: [macos-15-intel, windows-latest, ubuntu-latest, macos-latest]
         python-version: ['3.9', '3.12']
     runs-on: ${{ matrix.os }}
     steps:
@@ -82,7 +82,7 @@ jobs:
       env:
         SIMPLE_ITK_MEMORY_CONSTRAINED_ENVIRONMENT: 1
       run: | # pyenchant has a problem locating libenchant on macOS-ARM64. setting this environment variable resolves the issue
-        if [ "$RUNNER_OS" == "macOS" ] && [ "${{ matrix.os }}" != "macos-13" ]; then
+        if [ "$RUNNER_OS" == "macOS" ] && [ "${{ matrix.os }}" != "macos-15-intel" ]; then
            export PYENCHANT_LIBRARY_PATH=/opt/homebrew/lib/libenchant-2.dylib
         fi
         test_files="${{ steps.nbl.outputs.all_changed_files }}"
diff --git a/.github/workflows/scheduled_or_manual.yml b/.github/workflows/scheduled_or_manual.yml
index 71de562d..fc48b55b 100644
--- a/.github/workflows/scheduled_or_manual.yml
+++ b/.github/workflows/scheduled_or_manual.yml
@@ -34,8 +34,8 @@ jobs:
   test:
     needs: lint
     strategy:
-      matrix: #using macos-13, last available intel architecture. macos-latest is arm64 architecture.
-        os: [macos-13, windows-latest, macos-latest]
+      matrix: #using macos-15-intel, last available intel architecture. macos-latest is arm64 architecture.
+        os: [macos-15-intel, windows-latest, macos-latest]
         python-version: ['3.9', '3.12']
         inputs: ["00_ or 01_ or 02_ or 03_ or 04_ or 05_ or 10_ or 20_ or 21_ or 22_ or 300_ or 30_ or 31_ or 32_ or 33_ or 34_ or 35_ or 36_", "51_ or 55_ or 56_ or 60_ or 61_ or 62_ or 63_ or 64_", "65_ or 66_ or 67_ or 68_ or 69_ or 70_ or 71_"]
     runs-on: ${{ matrix.os }}
@@ -79,7 +79,7 @@ jobs:
       env: 
         SIMPLE_ITK_MEMORY_CONSTRAINED_ENVIRONMENT: 1
       run: | # pyenchant has a problem locating libenchant on macOS-ARM64. setting this environment variable resolves the issue
-        if [ "$RUNNER_OS" == "macOS" ] && [ "${{ matrix.os }}" != "macos-13" ]; then
+        if [ "$RUNNER_OS" == "macOS" ] && [ "${{ matrix.os }}" != "macos-15-intel" ]; then
            export PYENCHANT_LIBRARY_PATH=/opt/homebrew/lib/libenchant-2.dylib
         fi
         pytest -v --tb=short -k "${{matrix.inputs}}" tests/test_notebooks.py::Test_notebooks::test_python_notebook