How to Defog a Car Windscreen & Stop Condensation in Winter
A 10-step guide to defogging your car windscreen in the winter.
- Make sure your car heater is being utilised, set it to maximum power and direct the airflow to the windscreen.
- Use your rear window heater to quickly clear fog from the rear window.
- Switch on the air conditioning to dehumidify the air inside the car.
- Open the windows slightly to allow cold air to balance temperatures and reduce fogging.
- Remove grime to prevent condensation build-up by cleaning your windows regularly.
- Place dehumidifying pods in your car to absorb excess moisture.
- Inspect door and window seals for potential moisture entry, checking for leaks.
- Leave damp clothes or shoes outside the car.
- Keep the recirculation setting off. Use fresh air mode to reduce humidity inside.
- Start the engine early to warm the interior and prevent fogging.
Winter brings snug evenings on sofas, chilly walks wrapped in wool, and (unfortunately) a lot of time spent warming up our cars! Besides waiting longer for the engine to warm up and constantly being on alert for black ice, one of the biggest challenges drivers face is keeping car windows condensation-free.
Condensation not only makes it difficult to see, but it also adds precious minutes to your morning routine as you wait for the mist to clear before you can safely hit the road. Wet weather, snow, and the need to keep your windows closed to stay warm all contribute to a build-up of moisture inside your car.
Let's explore how to stop condensation and keep your windows clear, ensuring a safer and more enjoyable driving experience.
Where does condensation come from?
It helps to understand what causes your windscreen and windows to fog up if you’re going to take steps to avoid it. Fundamentally, condensation forms on surfaces where two different temperatures meet. The outside air in winter, for example, is generally quite cold – and, while the internal temperature of your car isn’t usually high enough for condensation to form when you get in, the warmth of your body and breath usually increases the temperature just enough to cause condensation.
Think about it this way: your breath is roughly the same temperature as your body – so any moisture in your breath and the air in front of it can be warm enough to stay as a vapour. But when you breathe into the cold outside air, you can often see your breath fog out in front of you.
The more humidity there is in your car’s air, the more (and more quickly) the windscreen and windows will fog up when you get in.
Is condensation in a car a problem?
Condensation forming isn’t a problem, but having a consistently humid car interior certainly might be. Besides the fact that it’ll take longer to defog your car, condensed water has to go somewhere – and that somewhere tends to be downwards towards areas with sensitive electrical or mechanical components. Over time, this can cause those components to rust, short circuit, and break.
So, it’s certainly worth keeping condensation to a minimum!
If you’re finding that your car takes excessively long to defog, or fogs up again quickly – a window or door seal may have perished and be letting in more air & moisture.
Below are some tips on ways you can defog a windscreen & stop as much condensation from forming.
Turn on your car heater
Your car’s heater works by drawing heat from the engine and passing that heat into your car's interior – so it often takes a minute or two to start getting hot because you have to wait for the engine to get hot.
To speed up the window demisting, set your heater to max power and turn it to the setting that directs all the output to the windscreen. This also has the added benefit of not blasting you directly with chilly air!
If all goes well, the mist should disappear within a few minutes, and you can get on with your drive.
Turn on your rear window heating element
Many modern cars come equipped with rear windows that have heating elements embedded within them. These elements are thin electrical wires that warm up when a current flows through them. Initially designed to melt frost and ice quickly, they are also highly effective at clearing fog from the rear window, improving visibility during colder months.
This feature was primarily designed to defrost rear windows but also works well to defog them! It is also useful in damp or frosty conditions when visibility is crucial. The heating system can be easily activated with the push of a button, providing a convenient solution for safer driving.
Use your air con
Heating the car vaporises the condensation so you can see through your windscreen, but this moisture doesn’t actually go anywhere. Every time you drive, you’re essentially adding to the moisture content of the car because (funnily enough) you have to breathe while driving.
This means that you get into a vicious cycle of warming up the air when you get in, only to have to warm it up more the next time you want to drive.
A clever way to reduce the moisture content of your car is to run the air con system. It seems counter-intuitive to actively blow cold air into the car, but the cold air isn’t what helps here: most air con systems have a dehumidifier in the cold circuit. So, even just leaving the air con running on cool for a few minutes while the engine warms up will dehumidify a lot before you get the heater on!
Another thing to try alongside the above tips is using dehumidifying pods. You can buy small, non-powered dehumidifier packs online or from many supermarkets; just pop one or two in your car to help keep any dampness at bay and replace them when they get full.
Open your windows
Condensation forms when there’s a temperature difference, so your choice is to either warm the car up enough that the windscreen becomes warm or cool the car down sufficiently so condensation doesn’t form. To do this (which is sometimes a faster solution) – simply open your car’s windows.
However, this comes with the main drawback that you then have to drive while being freezing – and this only works well if the outside air isn’t especially humid. For example, it won’t work particularly well if you’re stuck in fog or heavy rain.
Keep your windows clean
This is often surprising, but condensation takes a lot longer to clear from grime that’s accumulated on the inside of windows than it otherwise would because it has a lot more to hold on to!
Making sure your windows are clean not only helps you see better but helps avoid condensation clinging on.
Get your vehicle winter ready with Kwik Fit
Prepare your vehicle for winter with Kwik Fit. Winter driving brings challenges like reduced visibility, mechanical strain from cold temperatures, and treacherous conditions on wet, snowy, or icy roads.
Ensure your car is ready for the season with professional servicing and maintenance at your local Kwik Fit centre. From checking your tyres and brakes to ensuring your air con systems are in top condition, our experts will help you stay safe and comfortable on the road all winter long. Don’t wait for the cold to catch you off guard — book your appointment today and drive with confidence throughout the winter.
