How to demist car windows

The cause of your car windscreen misting up is actually down to water vapour in the atmosphere that occurs when your body heats the air inside the cabin – as does your breath – increasing the amount of moisture it can hold.

This means when it comes into contact with your windscreen it cools and condenses, forming a 'mist'. 

Here's how to clear your windscreen in double-quick time (with a helpful 'life hack' thrown in at the bottom, to help stop your windscreen misting up in the first place).

Start the heater off cold, then slowly increase the temperature as the air dries out, rather than overloading the cabin with hot, ‘wet’ air.

Try to find a temperature and humidity that’s comfortable but doesn’t mist up the cabin.

Make sure your heater's blast is directed at the windscreen and the windows - the warmer air (even on cold the air will be warmer than the ice cold windscreen) will dry the glass a little through evaporation and begin to heat up the glass to stop the water vapour condensing on it again.

Of course, if you're not in a rush and your frozen bones need warmth then use the hot air to warm both you and the windscreen.

It may take a little longer to clear fully but you will at least be a little more comfortable - just don’t move off until all glass surfaces on your car are clear. It’s dangerous and illegal if visibility is impeded.

If your car has air conditioning make sure it is switched on.

Use the air-con in conjunction with the heater. Hot air will dry the glass a little through evaporation, but the air will then cool down and condense on the glass once more, so make sure the air-con is on to keep the atmosphere inside dry.

If your windscreen is iced over, then the heat is obviously more necessary. But in this instance you might want to scrape the outside of your windscreen clear first - see our seven top tips to keep your windscreen clear in winter for more.

If you don’t have a clever climate control system, having the windows down could actually help clear the screen faster.

This helps because the dry, cold air from outside can help reduce the amount of water vapour inside the car, stopping the screen misting up.

Then you can begin to warm the car up gradually to a temperature that suits you after you have cleared the windscreen. 

Of course, you should never pull away with your vision impaired, but if your windows start to mist up during driving this is also a worthwhile tactic, for those without air-con. If the misting clouds too much of your vision you should pull over where safe to do so and wait for your windows to clear.

If you do have a clever climate control system, utilise it. There’ll most likely be a setting for demisting the windscreen, which will automatically adjust the ventilation system’s parameters to achieve the best results. 

Keeping your windscreen clean will go a long way to stopping it misting up in the first place.

A handy tip to go the extra mile is to actually clean your windscreen with shaving foam.

This protective barrier won't last forever and may need to be repeated regularly, but a windscreen cleaned with shaving foam will be less likely to mist up.

It's a little trick ice hockey players use to stop their face masks from steaming up when they're on the ice.

Take a clean towel and place a dollop of shaving foam onto it.

Wipe the windscreen with the towel, spreading the shaving foam over the entire surface.

Then take another clean towel and wipe off the shaving foam completely.

This protective barrier should help stop your windscreen from misting up, but it will need to be regularly reapplied to continue to work.