Climate and atmospheric monitoring at NOA began as early as the mid-19th century, with the systematic recording of daily meteorological and atmospheric observations in the center of Athens. In 1890, the 1st class historic meteorological station was permanently established in Thiseio, operating uninterrupted to this day. In 1953, the country’s first actinometric station began its operation on Pnyx Hill, while since 1999, an IERSD station has also been operating continuously in Penteli.

In 2006, the development of the surface automatic weather station network began, which now numbers more than 600 stations (June 2026) (https://www.meteo.gr/gmap.cfm). The network is continuously expanding to gradually cover the entire Greek territory, complementing the network of the Hellenic National Meteorological Service. The largest part of these automatic weather stations is integrated into the OSCAR database of the World Meteorological Organization and into the operational data assimilation of the European Centre for Medium-Range Weather Forecasts (ECMWF). The stations transmit their measurements continuously and in real time, with data recorded at 10-minute intervals.

At the same time, IERSD operates a network of actinometric stations across various locations in the country, as well as the HYDRONET network of hydrological telemetric stations (https://hydronet.noa.gr) that transmit real-time measurements.