diff --git a/.github/workflows/cibuildwheel.yml b/.github/workflows/cibuildwheel.yml
index 9c25318d..ade60a1d 100644
--- a/.github/workflows/cibuildwheel.yml
+++ b/.github/workflows/cibuildwheel.yml
@@ -34,18 +34,17 @@ jobs:
         fetch-depth: 0
 
     - name: "Building ${{ matrix.os }} (${{ matrix.arch }}) wheels"
-      uses: pypa/cibuildwheel@v2.15.0
+      uses: pypa/cibuildwheel@v2.16.5
       env:
         # Skips pypy py36,37
-        CIBW_SKIP: "pp* cp36-* cp37-* 
+        CIBW_SKIP: "pp* cp36-* cp37-*"
         CIBW_ARCHS: ${{ matrix.arch }}
-        CIBW_BUILD_FRONTEND: build
         CIBW_MANYLINUX_X86_64_IMAGE: manylinux2014
         CIBW_TEST_SKIP: "*_arm64"
         CIBW_TEST_REQUIRES: pytest
         CIBW_TEST_COMMAND: >
           python -c "import cftime; print(f'cftime v{cftime.__version__}')" &&
-          python -m pip install -r {package}/requirements-dev.txt &&
+          python -m pip install check-manifest cython pytest pytest-cov &&
           python -m pytest -vv {package}/test
 
     - uses: actions/upload-artifact@v3
diff --git a/.github/workflows/tests_conda.yml b/.github/workflows/tests_conda.yml
index 7e7ccb20..0e0275cc 100644
--- a/.github/workflows/tests_conda.yml
+++ b/.github/workflows/tests_conda.yml
@@ -8,15 +8,21 @@ on:
 jobs:
   run:
     runs-on: ${{ matrix.os }}
+    continue-on-error: ${{ matrix.experimental }}
     strategy:
       fail-fast: false
       matrix:
         python-version: [ "3.8", "3.9", "3.10", "3.11", "3.12" ]
         os: [windows-latest, ubuntu-latest, macos-latest]
         platform: [x64, x32]
+        experimental: [false]
         exclude:
           - os: macos-latest  
             platform: x32
+        include:
+          - python-version: "3.12"
+            os: "ubuntu-latest"
+            experimental: true
 
     steps:
     - uses: actions/checkout@v4
@@ -31,11 +37,22 @@ jobs:
           cython>=0.29.20
           pytest
           pytest-cov
+    - name: Install unstable dependencies
+      if: matrix.experimental == true
+      shell: bash -l {0}
+      run: |
+        python -m pip install \
+        --index-url https://pypi.anaconda.org/scientific-python-nightly-wheels/simple/ \
+        --trusted-host pypi.anaconda.org \
+        --no-deps --pre --upgrade \
+        numpy;
+        python -m pip install -v -e  . --no-deps --no-build-isolation --force-reinstall
 
     - name: Install cftime
+      if: matrix.experimental != true
       shell: bash -l {0}
       run: |
-        pip install -v -e  . --no-deps --force-reinstall
+        python -m pip install -v -e  . --no-deps --force-reinstall
 
     - name: Run Tests
       shell: bash -l {0}
diff --git a/.github/workflows/tests_latest.yml b/.github/workflows/tests_latest.yml
index 89a428a7..3090bf03 100644
--- a/.github/workflows/tests_latest.yml
+++ b/.github/workflows/tests_latest.yml
@@ -20,9 +20,15 @@ jobs:
       run: |
         python -m pip install --upgrade pip
 
-    - name: Install cftime dependencies via pip
+    - name: Install unstable cftime dependencies via pip
       run: |
-        python -m pip install -r requirements-dev.txt
+        python -m pip install --pre -r requirements-dev.txt
+        # get nightly wheels for numpy
+        python -m pip install \
+          --index-url https://pypi.anaconda.org/scientific-python-nightly-wheels/simple/ \
+          --trusted-host pypi.anaconda.org \
+          --no-deps --pre --upgrade \
+          numpy
 
     - name: Install cftime
       run: |
diff --git a/pyproject.toml b/pyproject.toml
index 8ad303bf..744dd8c9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,3 +1,9 @@
 [build-system]
-requires = ["setuptools>=41.2", "cython>=0.29.20", "wheel", "oldest-supported-numpy; python_version<'3.12.0.rc1'", "numpy>=1.26.0b1; python_version>='3.12.0.rc1'"]
+requires = [
+    "setuptools>=41.2",
+    "cython>=0.29.20",
+    "wheel",
+    "oldest-supported-numpy ; python_version < '3.9'",
+    "numpy>=2.0.0rc1,<3 ; python_version >= '3.9'",
+]
 build-backend = "setuptools.build_meta"
diff --git a/src/cftime/_cftime.pyx b/src/cftime/_cftime.pyx
index db79e9a0..eb5ad810 100644
--- a/src/cftime/_cftime.pyx
+++ b/src/cftime/_cftime.pyx
@@ -7,6 +7,7 @@ from cpython.object cimport (PyObject_RichCompare, Py_LT, Py_LE, Py_EQ,
 from numpy cimport int64_t, int32_t
 import cython
 import numpy as np
+cimport numpy as np
 import re
 import time
 from datetime import datetime as datetime_python
@@ -14,6 +15,8 @@ from datetime import timedelta, MINYEAR, MAXYEAR
 import warnings
 from ._strptime import _strptime
 
+np.import_array()
+
 microsec_units = ['microseconds','microsecond', 'microsec', 'microsecs']
 millisec_units = ['milliseconds', 'millisecond', 'millisec', 'millisecs', 'msec', 'msecs', 'ms']
 sec_units =      ['second', 'seconds', 'sec', 'secs', 's']