What’s the Fastest Way to Defog Car Windows?

Air conditioning is the key. Cold air may be the last thing you want in the winter, but remember, this mode isn’t called Chill—it’s “air conditioning” because it dehumidifies the air. You can still set the temperature to a comfortable level and enjoy warm, dry air from the vents. 

If you’re adjusting the climate control system manually rather than just using Defrost, be sure to keep it in Fresh-Air mode, allowing outside air to enter the system. (This is the opposite of Recirculation mode, as indicated by the symbol of a car with a looped arrow within it. Recirc is great when following a filth-spewing diesel truck or passing by a stinky skunk, but it will make the fog condition worse.) Sometimes opening the windows slightly, especially if the car is full of passengers, may be all the conditioning you need.

Resist the urge to rub a cloth on the windshield, because that can lead to streaks that can obscure your view in direct sunlight or possibly when driving toward headlights.