This article presents results from a study on thermal performance of several LED traffic light heads. Thermal performance of an electronic equipment, especially LED luminaire, is a lifetime determining criteria. In order to simulate real life worst case scenario signal heads are placed in thermal chamber and the internal temperature is set to 60oC. A controller is made to control the LED signal heads with longest time sequences according to statutory requirements. Constant light mode is studied also. Measurements are made with infrared camera and thermocouple for verification. The measured solder point temperatures are used to calculate junction temperatures and estimate dangerous operating conditions.