The main goal of these papers is to analyze the Free space optical system with the weather condition of Ankara, the capital city of turkey. Governmental meteorological data support the analysis of this study of wireless communication systems; where it provides real measurement values. The advantages of the FSO system are the simplicity and the cost of installation in comparison with fiber optic systems that use light amplified as a source for transmission. This system is used in short-range applications, which are between buildings in cities or between skyscrapers, and sometimes between ships, as well as very complex military situations. The laser generally is used as a signal transmitter because it has a special optical advantage that allows it to travel long distances. Telecommunications engineers normally prefer to use semiconductor lasers because of their special properties and their cost-effectiveness. The obstacles that face the FSO system are different weather conditions such as rain, fog, air molecules, and snow. This study will investigate the FSO using a semiconductor laser according to the weather conditions of Ankara and the distance traveled taking into account a good high-quality data transmission.