diff --git a/.github/workflows/python-publish.yml b/.github/workflows/python-publish.yml
index 3bfabfc..96caa82 100644
--- a/.github/workflows/python-publish.yml
+++ b/.github/workflows/python-publish.yml
@@ -1,11 +1,6 @@
 # This workflow will upload a Python Package using Twine when a release is created
 # For more information see: https://help.github.com/en/actions/language-and-framework-guides/using-python-with-github-actions#publishing-to-package-registries
 
-# This workflow uses actions that are not certified by GitHub.
-# They are provided by a third-party and are governed by
-# separate terms of service, privacy policy, and support
-# documentation.
-
 name: Upload Python Package
 
 on:
@@ -18,9 +13,11 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
     - name: Set up Python
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v4
       with:
         python-version: '3.x'
     - name: Install dependencies
@@ -30,7 +27,7 @@ jobs:
     - name: Build package
       run: python -m build
     - name: Publish package
-      uses: pypa/gh-action-pypi-publish@27b31702a0e7fc50959f5ad993c78deac1bdfc29
+      uses: pypa/gh-action-pypi-publish@release/v1
       with:
         user: __token__
         password: ${{ secrets.PYPI_API_TOKEN }}
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..3725811
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,29 @@
+name: Tests
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.9", "3.11", "3.12"]
+
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v4
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install -e ".[test]"
+    - name: Run tests
+      run: pytest
diff --git a/.gitignore b/.gitignore
index 98916bf..a88c730 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,7 +1,8 @@
 *.swp
 *__pycache__
 python/*.pyc
-gfdlvitals.egg-info/
+*.egg-info/
+.venv/
 testing/test_data
 testing/db
 testing/db-esm2
diff --git a/.readthedocs.yml b/.readthedocs.yml
index f94758f..97c3631 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -9,8 +9,13 @@ version: 2
 sphinx:
   configuration: docs/source/conf.py
 
-# Optionally set the version of Python and requirements required to build your docs
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+
 python:
-  version: 3.8
   install:
+    - method: pip
+      path: .
     - requirements: docs/requirements.txt
diff --git a/docs/requirements.txt b/docs/requirements.txt
index 910fbf5..c2e0ad0 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,10 +1,11 @@
-cftime<=1.2.1
+cftime
 ipython
 jupyter
 matplotlib>=3.3.3
-nc-time-axis<=1.2.0
-netCDF4 
+nc-time-axis
+netCDF4
 numpy
 pandas
 scipy
+sphinx-rtd-theme
 xarray
diff --git a/docs/source/conf.py b/docs/source/conf.py
index 88b7b68..f6dd15b 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -11,9 +11,7 @@
 # documentation root, use os.path.abspath to make it absolute, like shown here.
 #
 import os
-import sys
-print(os.getcwd())
-sys.path.insert(0, os.path.abspath('../../'))
+from importlib.metadata import version as _get_version
 
 
 # -- Project information -----------------------------------------------------
@@ -23,7 +21,8 @@
 author = 'John Krasting'
 
 # The full version, including alpha/beta/rc tags
-release = '3.0a1'
+release = _get_version("gfdlvitals")
+version = release
 
 
 # -- General configuration ---------------------------------------------------
@@ -67,4 +66,6 @@
 
 #-- Build api
 from sphinx.ext.apidoc import main
-main(['-f', '-M', '-e', '-T', '../../gfdlvitals', '-o', 'api' ])
\ No newline at end of file
+import gfdlvitals
+_pkg_dir = os.path.dirname(gfdlvitals.__file__)
+main(['-f', '-M', '-e', '-T', _pkg_dir, '-o', 'api' ])
\ No newline at end of file
diff --git a/docs/source/plotting.rst b/docs/source/plotting.rst
index 8648871..66e5779 100644
--- a/docs/source/plotting.rst
+++ b/docs/source/plotting.rst
@@ -15,6 +15,7 @@ options to smooth the data, overlay a trend line, and align offset
 time axes.
 
 .. ipython:: python
+   :okexcept:
 
    import gfdlvitals
 
diff --git a/docs/source/vitals_data_frame.rst b/docs/source/vitals_data_frame.rst
index f05be4c..eeb12d4 100644
--- a/docs/source/vitals_data_frame.rst
+++ b/docs/source/vitals_data_frame.rst
@@ -138,6 +138,7 @@ In the example below, the test historical dataset is artifically split
 into two 20-year epochs for comparison.
    
 .. ipython:: python
+   :okexcept:
 
    df_hist_t0 = df_hist[-40:-20]
    df_hist_t1 = df_hist[-20::]
diff --git a/gfdlvitals/__init__.py b/gfdlvitals/__init__.py
index 9d672db..5c412ad 100644
--- a/gfdlvitals/__init__.py
+++ b/gfdlvitals/__init__.py
@@ -1,6 +1,11 @@
 """gfdlvitals - a package for computing global mean metrics"""
 
-from .version import __version__
+from importlib.metadata import version, PackageNotFoundError
+
+try:
+    __version__ = version("gfdlvitals")
+except PackageNotFoundError:
+    __version__ = "unknown"
 
 from . import averagers
 from . import cli
diff --git a/gfdlvitals/cli.py b/gfdlvitals/cli.py
index 6cb7bf0..7fd399b 100755
--- a/gfdlvitals/cli.py
+++ b/gfdlvitals/cli.py
@@ -5,10 +5,11 @@
 import os
 import shutil
 import subprocess
+import sys
 import tempfile
 import gfdlvitals
 
-__all__ = ["arguments", "process_year", "run"]
+__all__ = ["arguments", "process_year", "run", "main"]
 
 
 def arguments(args=None):
@@ -195,3 +196,9 @@ def run(args):
     # -- Clean up
     os.chdir(cwd)
     shutil.rmtree(tempdir)
+
+
+def main():
+    """Entry point for the gfdlvitals command"""
+    sys.stdout.reconfigure(line_buffering=True)
+    run(sys.argv[1:])
diff --git a/scripts/db2nc b/gfdlvitals/cli_db2nc.py
old mode 100755
new mode 100644
similarity index 90%
rename from scripts/db2nc
rename to gfdlvitals/cli_db2nc.py
index 337e1d5..55534d1
--- a/scripts/db2nc
+++ b/gfdlvitals/cli_db2nc.py
@@ -1,6 +1,4 @@
-#!/usr/bin/env python3
-
-""" Command line utility to convert SQLite to NetCDF """
+"""Command line utility to convert SQLite to NetCDF"""
 
 import argparse
 import os
@@ -12,7 +10,7 @@
 
 
 def arguments():
-    """Function captures the command-line aguments passed to this script"""
+    """Function captures the command-line arguments passed to this script"""
 
     description = """
     Program for converting .db file format to NetCDF format.
@@ -24,12 +22,10 @@ def arguments():
         description=description, formatter_class=argparse.RawTextHelpFormatter
     )
 
-    # -- Input tile
     parser.add_argument(
         "infile", type=str, help="Input file. Format must be sqlite (*.db)"
     )
 
-    # -- Output file
     parser.add_argument(
         "-o",
         "--outfile",
@@ -122,9 +118,6 @@ def write_nc(
     ncfile = nc.Dataset(outfile, "w", format=ncformat)
     ncfile.setncattr("source_file", dbfile)
     ncfile.setncattr("created", timestamp_str)
-    # ncfile.setncattr('experiment',expName)
-    # ncfile.setncattr('type',plotType)
-    # ncfile.setncattr('region',region)
     _ = ncfile.createDimension("time", 0)
     time = ncfile.createVariable("time", "f4", ("time",))
     time.calendar = "noleap"
@@ -134,9 +127,6 @@ def write_nc(
         if table not in ["long_name", "units", "cell_measure"]:
             data_array = np.ma.ones(len(years)) + 1.0e20
             data_array.mask = True
-            # if 'Land' in plotType:
-            #  extract_list = ['avg','sum']
-            # else:
             extract_list = ["value"]
             for k in extract_list:
                 count = 0
@@ -178,16 +168,15 @@ def write_nc(
     ncfile.close()
 
 
-if __name__ == "__main__":
-
-    # read command line arguments
+def main():
+    """Entry point for the db2nc command"""
     args = arguments()
-    # get the full path of the db file
     infile = os.path.realpath(args.infile)
-    # get list of variables and years in a file
     _tables, _years = tables_and_years(infile)
     write_nc(
         infile, args.outfile, _tables, _years, clobber=args.force, verbose=args.verbose
     )
 
-sys.exit()
+
+if __name__ == "__main__":
+    main()
diff --git a/scripts/plotdb b/gfdlvitals/cli_plotdb.py
old mode 100755
new mode 100644
similarity index 93%
rename from scripts/plotdb
rename to gfdlvitals/cli_plotdb.py
index bb56658..5434a79
--- a/scripts/plotdb
+++ b/gfdlvitals/cli_plotdb.py
@@ -1,15 +1,10 @@
-#!/usr/bin/env python
-
-""" CLI script for plotting SQLite files """
+"""CLI script for plotting SQLite files"""
 
 import argparse
 import os
 
-import matplotlib.pyplot as plt
-
 import gfdlvitals
 
-COUNT = 1
 
 def arguments():
     """
@@ -79,7 +74,11 @@ def arguments():
     return args
 
 
-
-if __name__ == "__main__":
+def main():
+    """Entry point for the plotdb command"""
     cliargs = arguments()
     gfdlvitals.plot.run_plotdb(cliargs)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/gfdlvitals/plot.py b/gfdlvitals/plot.py
index eed6e9b..fd7685c 100644
--- a/gfdlvitals/plot.py
+++ b/gfdlvitals/plot.py
@@ -5,7 +5,7 @@
 import nc_time_axis
 
 import numpy as np
-import pkg_resources as pkgr
+from importlib.resources import files
 
 import matplotlib
 import matplotlib.pyplot as plt
@@ -21,7 +21,7 @@
 def set_font():
     """Sets font style to Roboto"""
     # Add Roboto font
-    fonts_dir = pkgr.resource_filename("gfdlvitals", "resources/fonts")
+    fonts_dir = str(files("gfdlvitals").joinpath("resources/fonts"))
 
     font_dirs = [fonts_dir]
     font_files = font_manager.findSystemFonts(fontpaths=font_dirs)
diff --git a/gfdlvitals/sample.py b/gfdlvitals/sample.py
index ab6135b..72ecedd 100644
--- a/gfdlvitals/sample.py
+++ b/gfdlvitals/sample.py
@@ -1,6 +1,6 @@
 """ Sample db files for demonstration """
 
-import pkg_resources as pkgr
+from importlib.resources import files
 
-historical = pkgr.resource_filename("gfdlvitals", "resources/historical.db")
-picontrol = pkgr.resource_filename("gfdlvitals", "resources/picontrol.db")
+historical = str(files("gfdlvitals").joinpath("resources/historical.db"))
+picontrol = str(files("gfdlvitals").joinpath("resources/picontrol.db"))
diff --git a/gfdlvitals/util/gmeantools.py b/gfdlvitals/util/gmeantools.py
index 63c06f0..4c15835 100644
--- a/gfdlvitals/util/gmeantools.py
+++ b/gfdlvitals/util/gmeantools.py
@@ -3,10 +3,11 @@
 import math
 import pickle
 import sqlite3
+import sys
 import warnings
 
 import numpy as np
-import pkg_resources as pkgr
+from importlib.resources import files
 
 __all__ = [
     "get_web_vars_dict",
@@ -29,9 +30,7 @@ def get_web_vars_dict():
     dict
         LM3 variable module mappings and metadata
     """
-    mapping_file = pkgr.resource_filename(
-        "gfdlvitals", "resources/LM3_variable_dictionary.pkl"
-    )
+    mapping_file = str(files("gfdlvitals").joinpath("resources/LM3_variable_dictionary.pkl"))
     return pickle.load(
         open(
             mapping_file,
@@ -285,16 +284,12 @@ def write_sqlite_data(
     # check if result is a nan and replace with a defined missing value
     if varmean is not None:
         if math.isnan(float(varmean)):
-            warnings.warn(
-                f"Could not update {sqlfile} variable {varname} with mean={varmean}"
-            )
+            print(f"  WARNING: {varname} mean is NaN in {sqlfile}, writing missing value", file=sys.stderr)
             varmean = missing_value
 
     if varsum is not None:
         if math.isnan(float(varsum)):
-            warnings.warn(
-                f"Could not update {sqlfile} variable {varname} with mean={varsum}"
-            )
+            print(f"  WARNING: {varname} sum is NaN in {sqlfile}, writing missing value", file=sys.stderr)
             varsum = missing_value
 
     conn = sqlite3.connect(sqlfile)
diff --git a/gfdlvitals/util/netcdf.py b/gfdlvitals/util/netcdf.py
index 7cf4ffe..5b33a4c 100644
--- a/gfdlvitals/util/netcdf.py
+++ b/gfdlvitals/util/netcdf.py
@@ -73,10 +73,11 @@ def in_mem_xr(data):
         In-memory xarray dataset object
     """
 
+    time_coder = xr.coders.CFDatetimeCoder(use_cftime=True)
     if isinstance(data, netCDF4._netCDF4.Dataset):
-        dfile = xr.open_dataset(xr.backends.NetCDF4DataStore(data), use_cftime=True)
+        dfile = xr.open_dataset(xr.backends.NetCDF4DataStore(data), decode_times=time_coder, decode_timedelta=False)
     else:
-        dfile = xr.open_dataset(data, use_cftime=True)
+        dfile = xr.open_dataset(data, decode_times=time_coder, decode_timedelta=False)
 
     return dfile
 
diff --git a/gfdlvitals/util/xrtools.py b/gfdlvitals/util/xrtools.py
index 03bcbac..5dfecb6 100644
--- a/gfdlvitals/util/xrtools.py
+++ b/gfdlvitals/util/xrtools.py
@@ -97,6 +97,6 @@ def xr_weighted_avg(dset, weights):
             _dset_weighted[x] = _dset_weighted[x].astype(dset[x].dtype)
             _dset_weighted[x].attrs = dset[x].attrs
 
-        result = result.merge(_dset_weighted)
+        result = result.merge(_dset_weighted, compat="override")
 
     return result
diff --git a/gfdlvitals/version.py b/gfdlvitals/version.py
deleted file mode 100644
index 8357025..0000000
--- a/gfdlvitals/version.py
+++ /dev/null
@@ -1,3 +0,0 @@
-"""momlevel: version information"""
-
-__version__ = "3.0.12"
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..649d02f
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,77 @@
+[build-system]
+requires = ["setuptools>=64", "setuptools-git-versioning>=2.0"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "gfdlvitals"
+dynamic = ["version"]
+description = "Tools for calculating scalar diagnostics from GFDL models"
+readme = {content-type = "text/x-rst", text = """
+**gfdlvitals** is a Python package in the public domain
+that provides tools for calculating, storing, and analyzing
+scalar diagnostics from GFDL's CM4-class models.
+
+More Information
+----------------
+- Source code: `<https://github.com/jkrasting/gfdlvitals>`_
+- Documentation: `<https://gfdlvitals.readthedocs.io/en/latest/>`_
+"""}
+requires-python = ">=3.9"
+authors = [{name = "John Krasting", email = "john.krasting@noaa.gov"}]
+keywords = ["climate", "model", "analysis", "scalar", "diagnostics", "gfdl", "AM4", "CM4", "ESM4", "OM4", "LM4"]
+classifiers = [
+    "Development Status :: 5 - Production/Stable",
+    "Intended Audience :: Science/Research",
+    "Topic :: Scientific/Engineering",
+    "License :: Public Domain",
+    "Programming Language :: Python :: 3.9",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
+]
+dependencies = [
+    "numpy",
+    "scipy",
+    "h5netcdf",
+    "pandas",
+    "netCDF4",
+    "matplotlib",
+    "xarray",
+    "cftime",
+    "nc-time-axis",
+    "xgcm",
+    "regionmask",
+    "xoverturning",
+]
+
+[project.optional-dependencies]
+test = ["pytest"]
+
+[project.urls]
+Homepage = "https://github.com/jkrasting/gfdlvitals"
+Documentation = "https://gfdlvitals.readthedocs.io/en/latest/"
+
+[project.scripts]
+gfdlvitals = "gfdlvitals.cli:main"
+db2nc = "gfdlvitals.cli_db2nc:main"
+plotdb = "gfdlvitals.cli_plotdb:main"
+
+[tool.setuptools.packages.find]
+include = ["gfdlvitals*"]
+
+[tool.setuptools.package-data]
+gfdlvitals = [
+    "resources/LM3_variable_dictionary.pkl",
+    "resources/historical.db",
+    "resources/picontrol.db",
+    "resources/fonts/Roboto/*",
+    "resources/fonts/Roboto_Condensed/*",
+]
+
+[tool.setuptools-git-versioning]
+enabled = true
+dev_template = "{tag}.dev{ccount}+{sha}"
+dirty_template = "{tag}.dev{ccount}+{sha}.dirty"
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
diff --git a/scripts/gfdlvitals b/scripts/gfdlvitals
deleted file mode 100755
index d59c671..0000000
--- a/scripts/gfdlvitals
+++ /dev/null
@@ -1,10 +0,0 @@
-#!/usr/bin/env python3
-
-""" Command Line Script for running gfdlvitals """
-
-import sys
-import gfdlvitals.cli as cli
-
-if __name__ == "__main__":
-    cli.run(sys.argv[1::])
-    sys.exit()
diff --git a/setup.cfg b/setup.cfg
deleted file mode 100644
index c2be97e..0000000
--- a/setup.cfg
+++ /dev/null
@@ -1,56 +0,0 @@
-[metadata]
-name = gfdlvitals
-description = Tools for calculating scalar diagnostics from GFDL models
-url = https://github.com/jkrasting/gfdlvitals
-author = John Krasting
-author_email = john.krasting@noaa.gov
-keywords = climate model analysis scalar diagnostics gfdl AM4 CM4 ESM4 OM4 LM4
-classifiers =
-    Development Status :: 5 - Production/Stable
-    Intended Audience :: Science/Research
-    Topic :: Scientific/Engineering
-    License :: Public Domain
-    Programming Language :: Python :: 3.7
-    Programming Language :: Python :: 3.8
-    Programming Language :: Python :: 3.9
-long_description_content_type=text/x-rst
-long_description =
-    **gfdlvitals** is a Python package in the public domain
-    that provides tools for calculating, storing, and analyzing
-    scalar diagnostics from GFDL's CM4-class models. 
-
-    More Information
-    ----------------
-    - Source code: `<https://github.com/jkrasting/gfdlvitals>`_
-    - Documentation: `<https://gfdlvitals.readthedocs.io/en/latest/>`_
-
-[options]
-packages = find_namespace:
-zip_safe = False
-include_package_data = True
-python_requires = >=3.7
-install_requires =
-    setuptools
-    numpy
-    scipy
-    h5netcdf
-    pandas
-    netCDF4 
-    matplotlib
-    xarray
-    cftime
-    nc-time-axis
-scripts = 
-    scripts/gfdlvitals
-    scripts/db2nc
-    scripts/plotdb
-setup_requires =
-    setuptools
-
-[options.package_data]
-gfdlvitals =
-    resources/LM3_variable_dictionary.pkl
-    resources/historical.db
-    resources/picontrol.db
-    resources/fonts/Roboto/*
-    resources/fonts/Roboto_Condensed/*
diff --git a/setup.py b/setup.py
deleted file mode 100644
index 68b182c..0000000
--- a/setup.py
+++ /dev/null
@@ -1,6 +0,0 @@
-""" setup script """
-import setuptools
-
-exec(open("gfdlvitals/version.py").read())
-
-setuptools.setup(version=__version__)
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_basic.py b/tests/test_basic.py
new file mode 100644
index 0000000..e4e1c33
--- /dev/null
+++ b/tests/test_basic.py
@@ -0,0 +1,40 @@
+"""Basic tests for gfdlvitals package"""
+
+import os
+
+
+def test_import():
+    import gfdlvitals
+
+
+def test_version_exists():
+    import gfdlvitals
+    assert isinstance(gfdlvitals.__version__, str)
+    assert len(gfdlvitals.__version__) > 0
+
+
+def test_submodule_imports():
+    from gfdlvitals import averagers
+    from gfdlvitals import cli
+    from gfdlvitals import models
+    from gfdlvitals import sample
+    from gfdlvitals import util
+
+
+def test_vitals_dataframe():
+    from gfdlvitals import VitalsDataFrame
+    df = VitalsDataFrame({"a": [1, 2, 3]})
+    assert len(df) == 3
+
+
+def test_sample_files_exist():
+    from gfdlvitals import sample
+    assert os.path.isfile(sample.historical)
+    assert os.path.isfile(sample.picontrol)
+
+
+def test_open_db():
+    from gfdlvitals import open_db, sample, VitalsDataFrame
+    df = open_db(sample.historical)
+    assert isinstance(df, VitalsDataFrame)
+    assert len(df) > 0