I know there is software like wgrib2 that will convert files in grib and grib2 format to NetCDF files, but I need to go the other way: from NetCDF to grib2, because the local weather offices here can only consume gridded data in grib2 format.
It appears that one solution could be in Python, using the NetCDF4-Python library (or other) to read the NetCDF files and using pygrib to write grib2.
Is there a better way?
After some more research, I ended up using the British Met Office "Iris" package (http://scitools.org.uk/iris/docs/latest/index.html) which can read NetCDF as well as OPeNDAP, GRIB and several other formats, and allows to save as NetCDF or GRIB.
Basically the code looks like:
import iris
cubes = iris.load('input.nc') # each variable in the netcdf file is a cube
iris.save(cubes[0],'output.grib2') # save a specific variable to grib
But if your netcdf file doesn't contain sufficient metadata, you may need to add it, which you can also do with Iris. Here's a full working example:
https://github.com/rsignell-usgs/ipython-notebooks/blob/master/files/Iris_CFSR_wave_wind.ipynb