The performance of gas turbines is greatly affected by the ambient air temperature. Information from the operating data showed an increase in the power output when the air temperature drops. The power output increased by 0.61 MW, and the heat rate decreased by 10.86 kcal/kWh for every 1 ℃ decrease in air temperature. This case study was conducted by simulating the Cycle-Tempo software. Simulations were performed for existing conditions, modified with eva-cooler system, fog-spray system, and mechanical chiller. A comparison of gas turbine performance for each of these conditions was done to determine the effect of modifications on the gas turbine’s performance. Variations of ambient air temperature used in the simulations correspond to the operating data. The simulation results showed that the utilization of inlet air cooling can increase power output and lower the gas turbine’s heat rate. The maximum net power output obtained from the utilization of mechanical chiller technology was 8.46%.