An improved vehicle safety device for activating an alarm when the temperature in the interior of a vehicle reaches an extreme value. The device includes a presence sensor for detecting the presence of a human or an animal in the interior of a vehicle and a temperature sensor for detecting the temperature in the vehicle interior. A controller is coupled to the presence detector, the temperature detector, and the vehicle ignition system for generating a hazardous-condition signal in response to an extreme-temperature condition in the vehicle when a human or an animal is in the vehicle and the vehicle engine is not running. An alarm module is connected to the controller for generating audible, visual, and wireless emergency-response signals when a hazardous condition is detected. The alarm module may also be further configured to create a door-unlocking signal.