Thermal power plants have delayed the coal that they will use at stockpiles mandatorily. If these coal stockpiles remain at the stockyards over a certain period of time, a spontaneous combustion can be started itself. Coal stocks under combustion threat can cost too much economically to coal companies. Therefore, it is important to take some precautions for saving the stockpiles from the spontaneous combustion. In this research a coal stockpile at Tuncbilek Thermal Power Plant which was formed in 5 m wide, 10 m long, and 3 m height with a weight of 120 tons to observe internal temperature changes with respect to time under normal atmospheric conditions. Later, internal temperature measurements were obtained at 20 points distributed all over two layers in the stockpile. The parameters, such as air temperature, humidity, atmosphere pressure, wind speed and direction, which are effective on the stockpiles, were measured and used to obtain the graphs of stockpiles' internal temperature.