An automated weather station was installed in January 2004 for the first time at the Destacamento Las Gru¬tas of Gendarmería Nacional, Province of Catamarca (26°52’35”S, 68°18’37”W, 4000 masl). From April to December, meteorological conditions on the mountain were observed in order to better understand the high-altitude subtropical meteorology. This article documents the design, installation, and operation of the weather station, and presents a discussion of the collected measurements. The analyzed variables were air temperature, maxima and minima temperatures, humidity, precipitation, wind, as well as the occurence of snow, registered by the staff at Gendarmería. Large daily variability was recorded in most variables, which is not unexpected given the geographical location. Daily fields of the NCEP /NCAR Reanalysis relate the dates of large variability to cold surges affecting the region. Hourly wind direction measurements show preferential directions of SW-NW, with the largest variability occurring during November and December, indicating that moisture enters the region from different sources.