Fiber Bragg Gratings (FBG) are approximately 1 cm in size and can easily be connected to conventional single-mode fiber. Although they are sensitive, they can be easily installed in any environment with their outdoor protection designs. Changes in physical sizes such as temperature and stress cause linear changes in FBG's central wavelengths. In FBG sensing systems, the detection of the central wavelength of the reflected signal is one of the most important research subjects. Although different approaches have been studied for the determination of the central wavelength of FBG, the most common approach is to accept the wavelength corresponding to the highest power value of the signal as central wavelength. Several techniques are used to determine the wavelenght with this highest power value. The most stable method among these methods is the Gaussian fitting method. In this study, the Gaussian fitting method for the determination of the central wavelength of FBG in response to temperature changes has been theoretically and experimentally examined. As a result, the temperature measurement was taken from 5 FBG arrays, the signals were processed, and the temperature detection system was realized.