An apparatus and method is provided for detecting a temperature range or a temperature of a railroad train wheel or bearing wherein infrared radiation radiating from the wheel or bearing of a train traversing a railroad track is indicative of a temperature range of the wheel or bearing. The apparatus comprises a sensor for sensing infrared radiation radiating from the wheel or bearing within two or more infrared wavelength ranges. The sensor generates signals indicative of the sensed infrared radiation in each of the wavelength ranges. A processor determines a temperature range or a temperature of the wheel or bearing from the generated signals. The method detects a temperature range of a railroad train wheel or bearing wherein infrared radiation radiating from the wheel or bearing of a train traversing a railroad track is indicative of the temperature range of the wheel or bearing. The method includes sensing infrared radiation radiating from the wheel or bearing within two or more wavelength ranges of the infrared radiation. Signals are generated that are indicative of the sensed infrared radiation in each infrared wavelength range. A temperature range or a temperature of the wheel or bearing is determined from the generated signals.