Diagnosis
The temperature sensor is in the camera, not the monitor. It is measuring heat generated by the camera's own electronics. Poor ventilation or direct sunlight exacerbates the error.
How to Fix It
You must provide better airflow around the camera. Ensure the camera is not placed inside a enclosed shelf, behind fabric, or directly against a wall. There should be at least 2 inches of clear space on all sides, especially around the back. Mount it on a wall bracket for optimal air circulation.
If That Didn't Work
You can apply a manual offset. Note the difference between the monitor reading and a known-accurate room thermometer. Eufy does not have a built-in calibration setting. You must mentally add or subtract the offset. For example, if it always reads +8 degrees high, subtract 8 from the displayed value.
Heads Up
The temperature reading is an approximation for comfort, not a precision medical device. It is most accurate when the camera has been powered on and stable in its location for over 2 hours, allowing its internal temperature to stabilize.