During monsoons and winter, it is very common for the car windshield to fog
It is a result of difference between humidity and temperature inside and outside the car
To defog the windshield, you can increase the AC temperature inside the cabin
It results in warm air blowing inside the cabin and hitting the windshield, in turn raising temperature
In case the outside humidity is lower than the cabin of the car, open window for a bit
The AC inside the car cabin can be used as a dehumidifier
Majority of modern cars today come with climate controls
Another way is to make sure the engine temperature is around 90 degrees celsius
This will allow the car's windshield to defog quickly and properly