The Western Turkey Mesonet was initiated in 2002 as part of the Turkey Emergency Flood and Earthquake Recovery project. Its main goal is to provide agricultural and meteorological data not only to support flood forecasting/warning applications but also meteorological uses such as nowcasting and/or short-range forecasting. Currently, it is operational in the western part of Turkey at 206 sites: 4 groups with different types of parameter configuration, providing observations at either 1 or 10 min periods. The observations are transferred to the Turkish State Meteorological Service headquarters by one of the communication technologies available at the site: VSAT (Very Small Aperture Terminal), GPRS (General Packet Radio Service) or ADSL (Asymmetric Digital Subscriber Line). The quality control of the mesonet data is performed monthly in two ways, by an automated quality control test run and through manual quality control checks. Automated quality control tests (range, step, persistence, like-instrument and spatial) are run using not only spatial (site to site) but also temporal (month to month) varying thresholds. The confidence level of the observation quality is classified by one of the flag types ‘good’, ‘suspicious’ or ‘bad’ with respect to the test applied. Observations noted as ‘suspicious’ or ‘bad’ are cross checked in the manual quality control check stage and either confirmed as ‘bad’ or updated to ‘good’. The thresholds of the quality control tests for the corresponding sites are also updated where needed.