Although evolution in electrical power generation now continuously focuses on renewable resources, thermal power plants depending on typical fuels cannot be neglected. Market demand and their operational flexibility are the reasons why this type energy generation is worth investigating. This paper estimates the impact of intake ambient conditions on a combined cycle power plant (CCPP). Particularly, the investigation evaluates the effects of intake air ambient temperature and relative humidity in the context of the energy and electricity systems in Syria, specifically for the Jandar power plant. For an ambient temperature change from 3 degrees C to 42 degrees C, a standard temperature variation in the middle of Syria, the thermal efficiency of the CCPP is reduced from 53.3% to 45.7% at constant relative humidity of 60%. The net power output produced decreases from 00 MW at 15 degrees C to 252.6 MW at 42 degrees C. Although the amount of fuel consumed by combustion in the plant is reduced, the heat rate as well as the specific fuel consumption (SFC) increases. The SFC increased by 2.4% with a 20% increase in temperature at a constant relative humidity. A 3 degrees C increase in temperature results in a 2.7% increase in the heat rate.