A temperature tag and system for sensing and reporting an internal temperature reading inside a container. The temperature tag mounts on an outside surface of the container, and a shaft with a temperature sensor extends through the side of the container and senses the internal temperature reading. A plurality of readings may be recorded at a predefined sampling rate and stored in a data memory. The temperature tag then sends the temperature readings to a reader device that presents the temperature readings to a user. The reader device may trigger the temperature tag to send the temperature readings with a signal such as an infrared (IR) signal, a radio frequency (RF) signal, and the like. The temperature readings may be analyzed in the temperature tag, the reader device, or may be downloaded to a computer to determine if an alarm condition exists.