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How Can I Keep My Car Windows From Fogging Up?

Humid air in the car leads to foggy windows.
Warm up your car outdoors, because harmful carbon monoxide exhaust gases can get trapped inside garages and become deadly to anyone inside the car.
In winter, keep snow out of the car as much as possible.
Cleaning the interior of your car windows may help prevent them from fogging up.
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  • Originally Written By: Tricia Ellis-Christensen
  • Revised By: G. Wiesen
  • Edited By: O. Wallace
  • Last Modified Date: 17 November 2014
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To keep your car windows from fogging up, there are three basic things to consider: how to prevent it, how to reduce it if it occurs, and how to remove it once it is there. You can help prevent fogging by reducing the amount of moisture in the vehicle. Although some may still occur, you can minimize it by drying out air inside the car. If you do end up with foggy windows, most vehicles have defoggers that you can use, and a dry towel may also be effective for wiping it away.

Preventing Foggy Windows

You can help keep your car windows from fogging up by cleaning the interior of the windows every one to two weeks. Car windows, like other parts of the vehicle, gather dust and oil through normal use. This buildup actually makes them more likely to fog, as it provides a base for moisture to accumulate on. During wet weather seasons, you should clean the windows once a week to help prevent your car windows from fogging up.

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Fog develops on windows because the air in the car is humid. This moisture comes from the breath of people in a car, and also from damp clothing, hair, and other items. Try to eliminate as much excess moisture as you can before getting into a car. Kick as much snow off of your shoes as possible during the winter, and vigorously shake rain from umbrellas, coats, and other items. Dehumidifier crystals, which draw moisture from the air, can also be kept in a small cup in your car.

Reducing Fog Buildup

One of the best methods to keep car windows from fogging is to use your car's defogger or defroster air setting. While the "recirculate" option may warm the inside of a car more quickly, it also keeps the moisture in the air. It's better to bring in air from outside the car, which is usually drier and warmed by the engine. Rolling down the windows a little bit can also help let in drier air; even 0.5 inch (1.27 centimeters) can make a noticeable difference. If it is raining or snowing heavily, however, this may be ineffective as it lets in moisture, so use the air conditioning or heating system.

It can also help to warm up the car before driving in cold weather, and turn on the defroster before the windows have the chance to fog up. Don’t do this in a closed garage, since carbon monoxide buildup from car exhaust is dangerous in an unventilated space. If you park your car outdoors in a safe neighborhood, start the engine and set the defogger a few minutes before you plan to leave. In some car models, a rear defogger can help keep back windows clear as well.

Eliminating Fog on Windows

When in a hurry, you can clear fog from windows by wiping down their interior surface with a clean, dry towel. This should only be done when absolutely necessary, however, as it won't necessarily prevent the windows from clouding up again. Defoggers work by warming the windows, which dramatically reduces how easily fog can form on them.

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Discuss this Article

anon938550
Post 8

Shaving foam wiped over mirrors in a bathroom will stop them steaming up. Will it work on car windows too, do you think?

anon356074
Post 7

Dry the interior as much as possible. Open two windows slightly if weather permits. Make sure the air from your blowers is coming from outside. Use dessicating crystals. Don't smoke in the car. Keep the windows clean. Remove any damp clothes. Dry mats over the house radiator if they get damp. Park the car with the rear facing the sun. Even parking below a street lamp can help. I dealt with this problem for years but the appliance of science helped me once I overcame the apathy. Hope this helps.

healthy4life
Post 6

@StarJo – I crank up early, too, and I run my rear defroster. My back windshield is usually just as foggy as the windows.

I like to watch the moisture on the windows and both windshields dry up. Once the process gets started, they clear up rather rapidly. It's like a domino effect!

wavy58
Post 5

I usually roll down a fogged window to wipe the fog off. If it's really cold outside, this delivers a sudden burst of bitterly cold air that helps make me more alert, so it's a bonus!

StarJo
Post 4

My husband keeps an old t-shirt in our car and uses it to wipe down foggy windows. If he is driving and I'm in the car, I will wipe them down for him.

Foggy windows happen most often on really cold mornings in our vehicle. As soon as we crank up, the fog starts to form.

We have to crank it up about five minutes before we leave and turn the defroster on warm. That way, by the time we are ready to leave, the windows will no longer be foggy, and the car will be warm inside.

giddion
Post 3

I have always struggled with the question of how to keep my car windows from fogging up. It's really hard to wipe down the inside of the windshield while driving, especially since your vision is impaired by the fog.

I didn't know that dehumidifier crystals existed. I am going to try these, because they sound like a simple solution.

anon38555
Post 2

I think it might be more cost efficient to use the heater set to use air from outside the car as then the electric blower motor is not needed as much, or at all, meaning less load on the alternator and so less fuel used so more cost effective. Cheers. Jeremy :)

anon26861
Post 1

Our Vauxhall Astra windows fog up really badly, apparently a well known fault with Astras, and the air always seems damp in the car.

We bought a large bag of dehumidifier crystals from Lakeland Plastics, put half of them in an open, plastic container on the floor of the car and after a few days they had sucked all the dampness out of the air. Eventually, after a few weeks, they get so wet that they have to be changed but at only around £5 a bag it's well worth it for safe, clear windows.

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