How do you detect iced windscreens?

[Maurits28 (Maurits)]

Reminded me of this topic:

Calculating dew point for demisting car window

Does anyone have any advice for a beginner to rules (and meteorology)? Background: I live in the UK, it’s cold and wet here between about October and March, and this means the inside of our car windows tend to mist up over night, when the outside air is cold, particularly if the car is not parked in a garage (as mine isn’t). The simple solution to this is to start the engine a few minutes before leaving, with the fan and A/C on maximum, blowing on the inside of the windscreen. Newer cars have b…