Radars provide localized, highly detailed, timely and three dimensional sensing and observing capability that no other meteorological monitoring system can provide. They are able to measure variations in precipitation rates at a resolution of a few square kilometres or better and at time cycles of the order of a few minutes. The provision of homogeneous, high quality data starts with the installation and use of appropriate radar technology for the local weather environment and conditions. This International Standard describes system performance of ground-based weather radar systems measuring the atmosphere using frequencies between 2 GHz and 10 GHz. These systems are suitable for area-wide detection of precipitation and other meteorological targets at different altitudes. This International Standard also describes ways to verify the different aspects of system performance including infrastructure. The purpose of this International Standard is wide and addresses organisations in all countries using weather radar. DIN ISO 19926-1 was prepared by ISO/TC 146 "Air Quality", SC 5 "Meteorology", under participation of German experts in WG 7 "Weather radar" (Chairmanship and Secretariat: DIN).