This data set contains the monthly climatology data of the primary forcing data for Phase 2 of the North American Land Data Assimilation System (NLDAS-2). The data are in 1/8th degree grid spacing. The temporal resolution is monthly, ranging from January to December. The NLDAS-2 monthly climatology data are the NLDAS-2 monthly data averaged over forty years (1981 - 2020). The file format is netCDF. The previous version of this dataset (NLDAS_MC 002) was a 30-year average and was stored in GRIB file format. A brief description about the NLDAS-2 hourly and monthly primary forcing data can be found from the NLDAS_FORA0125_H_2.0 and NLDAS_FORA0125_M_2.0 landing pages. Details about the generation of the NLDAS-2 forcing datasets can be found in Xia et al. (2012). For more information, please see the README Document.