Misty car windows in winter can be annoying and they’re also a safety hazard. Here are some tips on how to clear windscreen fog.
A debate has sparked this winter on social media in Australia and New Zealand on the best way to defog your car windscreen. After 1.3 million views and comments, there is no absolute answer on whether you should be using hot or cold air to defog your windscreen.
Some people think the best way to go is to have the air conditioner on, but the temperature set to warm, while others think it should be cold air only. Despite the differing viewpoints, the one thing we can all agree on is that demisting your windscreen before driving off is a necessity during these cold winter months.
The process of demisting your car’s windshield and windows is tedious and time-consuming. But, if you don’t do it, you can endanger other road users and yourself, as driving with a fogged-up windscreen can severely obstruct your vision.
So, let’s go back to basics and understand why windscreens fog up in the colder months, what you can do to defog your windscreen as fast as possible and maybe even debunk some myths along the way.
Why does my windscreen fog up?
Windscreen fog is a common issue during the winter months. The cause is down to the amount of moisture in the atmosphere and how much of it the air can hold. It gets humid in the warmer months because high-pressure air can hold more water vapour. However, in the colder months the low-pressure air doesn’t hold as much.
Your breath or even your steaming cup of hot beverage is full of water vapour and the cold air inside the car can’t contain all of it, so it ends up as condensation on glass surfaces. So, how do you get rid of the accumulated condensation?
How to get rid of condensation from your windscreen
The obvious answer is to wipe it off using a cloth, or even the sleeve of your top. But, while this may be an instant fix, your breath continues to pump more moisture in the air, so your windscreen starts fogging up again.
Here are some things you can do to get rid of condensation:
If your car has air conditioning and heating
- Switch on the air conditioning in your car (yes, even if it’s cold outside). It does more than just cool the air inside your car – it doubles as a dehumidifier! This is the fastest way to demist your windscreen.
- You can use your heater but there’s a method to it. Start with cold air when you turn it on, then slowly increase the temperature as the air dries out. Make sure the air blast is directed at the windscreen. Doing it this way prevents you from overloading your car’s cabin with hot, wet air.
- If your car has a demist function, use it, but remember it works the same way as mentioned above. It’ll start by blasting the cabin with cold air before working its way to warmer temperatures. Don’t try to reduce the temperature of the cold air and just leave it to work its magic.
No air conditioning and heating? No problem!
- Use your windows to defog your windscreen. Make sure to fully wind them down so the cold air from outside can help reduce the amount of water vapour inside the car. This will stop the windscreen from misting up, although it make take longer and you will get chilly from the outside air coming in.
If you want to save on fuel, turn off your air conditioning or heater once your windscreen clears. An air conditioner consumes more fuel, especially if it’s producing warm, dry air. You could also use your windows instead if you want to be extra economical with fuel consumption. Just make sure you’re dressed warmly!
If condensation is a big problem for your car, prevention is also possible. There are several sprays and treatments available that can help; just pop into your nearest car accessories store to find the right solution for your needs.
Things you shouldn’t do
Now that we’ve covered what you can try to demist your windscreen, let’s talk about what you shouldn’t do.
Don’t use your hands to wipe the windscreen. As we mentioned previously, you could use a cloth or your sleeve but it’s only a temporary fix. It’s the same for using your hands. Not only is not very effective, but the natural oils from your skin can also smear the windscreen, making visibility even worse.
Some people suggest you wind down your windows just an inch as you drive. This is a myth, and it doesn’t work, because you’re not letting in much air as you drive. This makes it almost impossible to clear. You need to wind your window down fully to clear your windscreen.
Whichever approach you decide to take, remember that you shouldn’t drive until the glass is clear. It’s dangerous for you and other road users and, if your visibility is completely impeded, it’s illegal too.