I am trying to get data from the NAM-NMM Dataset and am having a lot of trouble getting the data I want out of the grb2 files. How can I get a CSV file containing information like Probability of precipitation, Probability of freezing precipitation, TMAX, TMIN, etc... plus time of forecast for all latitudes and longitudes.
Use wgrib2. This has a command line switch to get output as csv file. This should be simple like this:-
wgrib2 -match "TMAX" -match "800 mb" /path/to/file.grib2 -csv name.csv