A bearing temperature monitoring system for detecting a temperature of bearing grease within a bearing housing. The bearing temperature monitoring system comprises a housing mountable to the bearing housing, a power source selectively outputting an electrical current, and an electrical circuit. The electrical circuit includes a temperature sensor component electrically coupled to the power source. The temperature sensor component can be responsive to a change in temperature such that the temperature sensor component opens or closes the electrical circuit at a predetermined temperature even in the absence of an applied electrical current. The electrical circuit further includes an alert device electrically coupled to the power source and the temperature sensor component that outputs an alert in response to the temperature sensor component.