Monthly means of HySN, a high resolution HYbrid SeNorge data set of daily near surface humidity and incident shortwave and longwave radiation, and surface pressure created by merging reanalysis data (Era-interim) with a national 1-by-1 km gridded temperature data set, SeNorge v2 (SeNorge v2.1 between 1979 and 2015, and SeNorge v2.0 from 2016). The assumptions and methods used to downscale humidity and longwave radiation are similar to those used in WATCH/PGMFD/NLDAS-1. The software used to compile the data is available at GitHub. The daily data is at doi.org/10.5281/zenodo.1970170. The data has the same projection as SeNorge, UTM33, and is stored for precipitation days, i.e. the datestamp is day-month-year 06 UTC and the variable represents average value of the preceding 24 hours.