How to demist a car windscreen

Not being able to see out of your car is as dangerous as it is illegal, so being able to quickly and fully demist a car’s windscreen is vital. Thankfully, modern cars are filled with a number of useful tools for clearing the fog from their windows, but some of these are more obvious than others. So, allow us to explain everything you need to know about demisting your car’s windscreen.

How to demist your windscreen and side windows in six easy steps

• Turn on the demist function: This one’s a no-brainer, but the following steps will work in tandem with your car’s built-in demisting function to expedite the process. While electronically demisting rear windscreens are commonplace, don’t forget to check if your car has a heated front windscreen, too, as this may be controlled by a separate button or sub-menu item.
• Fire up the fans: There’s an ongoing debate as to whether hot or cold air is more effective at demisting windows. The fact is that warmer air can absorb more water and moisture than cold, but dry cold air drawn in from outside will still help to reduce moisture in the car. So while it may take a few minutes for your car to warm up and produce hot air, having your fans on will help to clear the glass. Just make sure your vents are aimed at the windows and windscreen.
• Turn your air-conditioning on: Air-conditioning isn’t just useful in helping to cool your car down in the summertime, it will also help dry out the air inside the cabin, reducing the amount of fog on your windows.
• Turn off air recirculation: Recirculation will prolong the amount of time that moist air stays inside the cabin. The air outside your car is usually drier than the air inside, so pulling in this fresh air will help towards the demisting process.
• Open a window: Opening a window will help to bring in the dry air from outside, which will then gradually warm up and absorb moisture. This is an especially useful method if your car does not have air-conditioning to otherwise speed up the process.
• Stand outside of the car: While this might sound like a horrible idea during the winter months, standing outside the car before setting off can help with demisting. If we may put it bluntly, your breath is warm and wet, so removing yourself essentially removes additional moisture. However, never leave the car unattended while it’s unlocked and demisting, as opportunistic thieves have been known to hop in and drive away within an alarmingly short timeframe.

Many modern cars with climate control systems have a dedicated front de-misting function, and pressing this will optimise the system by speeding up the fans, activating the air-conditioning and redirecting the vents all via this single button. If your car has this, be sure to make use of it.

How can I stop my car windows fogging up?

It’s difficult to completely stop your car windows from fogging up, however there are a few products that can help to at least reduce the problem. Many companies sell anti-fog solutions that you apply to the inside of the windows to stop them misting up in the first place. 

If you have an older car or a convertible which is prone to fogging up, you could buy a small car dehumidifying box or bag which can help to absorb any moisture in the car before it hits the windscreen. We regularly test these products, so be sure to check out our list of the best dehumidifier pouches.

Can I drive with misted up windows?

Whichever approach you choose, remember not to move off until all your glass is clear. If your visibility is impaired while driving, you’ll be risking the safety of both yourself and other road users, and you could face a fine of up to £2,500.

Of course, windows can mist up while a car is on the move. While it’s unlikely that you’ll need to pull over, we strongly recommend that you start following the steps above to quickly remove it before the problem worsens.

What causes car windscreen misting?

Your car’s windscreen will mist up when the moisture from the air inside condenses on the glass. When the temperature inside is warmer than the outside, this phenomenon will occur, so its most common during the winter months when the heating is on and it’s cold outside. On the subject of ice, we also have a dedicated guide to de-icing a car, in case the moisture has turned a bit solid.

Excess dampness can also cause misting, and this can be caused by items such as clothing and upholstery. Poor air circulation can also contribute towards the issue.

How to fix a car that won’t demist

If your car simply refuses to demist, or moisture keeps reappearing incredibly quickly, this could be a sign of an underlying fault. Examples of problems that can result in excess misting are worn weatherproofing seals or faulty heating systems. If you believe your car has a fault, we recommend consulting a trusted garage.

Winter and wet weather driving tips

Getting ready for winter

What are your top tips for driving in bad weather? Let us know in the comments section below..