This guideline describes the general requirements on a weather station, namely with respect to the measured physical values (air chemical measurements are not discussed), the installation, the sensors and data recording, the quality control, and maintenance. In addition to the general requirements, typical designs of weather stations are separately described according to application. Moreover, the most common measurement variables to be taken into account and the appropriate sensors are discussed in more detail in specific parts of guideline VDI 3786 [T1 to T9]. A general introduction to the measurement of meteorological parameters within the context of environmental questions can be found in [T1]. The performance characteristics (e.g. measurement uncertainty, etc.) are also explained there. In particular cases, visual observations [T7] may also be necessary, partly to identify events whose measurement involves much effort, partly to simply get an estimate.