$ guix environment --ad-hoc netcdf python-netcdf4 python
substitute: updating substitutes from 'https://ci.guix.gnu.org'... 100.0%
The following derivation will be built:
   /gnu/store/kd17xvr921gllc4rbx0gyz8blcwja4px-profile.drv
The following profile hooks will be built:
   /gnu/store/c88ra1grc2j7c19sad6wyy8r8nxs9vpp-info-dir.drv
   /gnu/store/igny6wbyannm68vfcivlbqrv458fkw85-manual-database.drv
   /gnu/store/jxg2z11bzsmlwzirr0bavaz71if8rqdn-fonts-dir.drv
   /gnu/store/rqi5h6jxw031kwxqk9xfplihmdpv34sh-ca-certificate-bundle.drv
building CA certificate bundle...
building fonts directory...
building directory of Info manuals...
building database for manual pages...
building profile with 3 packages...
$ echo $PYTHONPATH
/gnu/store/8mmhriyv6z3ljdd6qcz6rk38x6bnlcmd-profile/lib/python3.7/site-packages
$ python
Python 3.8.2 (default, Feb 26 2020, 22:21:03)
[GCC 9.2.1 20200130] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from netCDF4 import Dataset
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/gnu/store/8mmhriyv6z3ljdd6qcz6rk38x6bnlcmd-profile/lib/python3.7/site-packages/netCDF4/__init__.py", line 3, in <module>
    from ._netCDF4 import *
ModuleNotFoundError: No module named 'netCDF4._netCDF4'
>>>