What head unit do you have paired to the Vision? What software version do you have the Vision?
With the head unit talking to the Vision try toggle the temperature unit of measure on the head unit from C to F and then back to C again. This should force the setting to be sent to the Vision.
There is a bug on the varia vision. It normally displays the temperature in F, however if your Edge or device is in Celsius, you can add another screen on the varia and include the temperature. There it will show correctly in Celsius. and after you go back to any other screen it will show on the top the correct celsius temperature.
