Hydrometeorological monitoring, as discussed here, describes the activities required to characterize the properties and processes of the hydrosphere as it exists in the three-dimensional mesoscale environment of the high-mountain catchment basins of the Hindu Kush-Himalaya (HKH) Mountains. Credible monitoring involves: (a) functional institutions; (b) operational instruments; (c) trained, motivated individuals; (d) scientific procedures; and (e) dedicated funding. Establishing a regional hydro-meteorological research facility in the HKH Mountains will involve developing solutions in the areas of integrated data collection and analysis procedures, instrument selection and placement, compatibility of monitoring instruments and procedures, training of personnel, procedures related to scale and modeling, ensuring accessibility of monitoring sites, and management, analysis, and archiving of the acquired data, all in the context of processes within the mountain basins, not in the adjacent lowlands. Mountain hydrometeorology is defined by a set of complex, three-dimensional, biophysical environments, produced by interactions among terrain, geology, and meteorology. The homogeneity seen from the distant lowlands becomes a complex mosaic of environments within the headwater basins. Altitude determines the properties of an atmospheric column extending upwards from a point within the mountains. These atmospheric properties determine the potential water and energy budgets at a point, or within a basin, in the mountains. Relief, slope aspect and angle, defines local topography.