Natural gas combined cycle power plants (CCPPs) are widely used to meet peak loads in electric energy production. Continuous monitoring of the output electrical power of CCPPs is a requirement for power performance. In this study, the role of ambient temperature change having the greatest effect on electric production is experimentally investigated for a natural gas CCPP. The plant has generated electricity for fourteen years and setup at 240 MW in Aliaga, Izmir, Turkey. Depending on the seasonal temperature changes, the study data were obtained from each gas turbine (GT), steam turbine (ST) and combined cycle blocks (CCBs) in the ambient temperature range of 8-23 degrees C. In electric energy production, an important decrease was in the GTs because of the temperature increase. This decrease indirectly affected the electric energy production of the STs. As a result, the efficiency of each GT, ST and CCB decreased, although the quantity of fuel consumed by the controllers in the plant was reduced. As a result of this data, it has been recommended and applied that additional precautions have been taken in the power plant to bring the air entering the combustion chamber to ideal conditions and necessary air cooling systems have been installed. (C) 2018 The Authors. Published by Elsevier Ltd.