How To Stop Car Windows from Fogging Up – & 6 Prevention Tips

Whether you live in a warm climate or cold weather, you’re not immune to car windows fogging up.

Let’s say it’s a brisk, sunny, winter morning. You leave the house, coffee-to-go in one hand, and you’re all ready for work. You get in, turn on the engine, and suddenly, you realize that you can’t see through your foggy windshield.

It feels like a fog bank has materialized inside! Needless to say, you’ll have to waste time defogging your car windows before you can go anywhere.

Close up on a car's fogging windshield from the inside

Driving with poor visibility can be very dangerous, for your own safety, that of your passengers, and that of anyone else who happens to be around you on the road at the time.

If you’re a last-minute kind of person, this could mean being late for work – and I think I speak for everyone here when I say that no one wants any of the drama that comes with that …

Not to worry, though – you’ve come to the right place!

This article will let you in on all the reasons why your car windows fog up, will show you what to do when this happens, and we’ll also give you some very valuable tips on how to keep this from happening in the future.

Why Do Car Windows Fog Up?

We all know how annoying it is when we turn on our engines and see fogged windows.

This could happen both on the inside or on the outside, and it’s the result of water condensing on the glass.

When the moisture inside the car comes into contact with the cooler glass surface, condensation forms on the inside. On the other hand, if it’s warmer outside than it is inside the car, water will condensate on the outside of the glass.

Either way, driving with poor visibility can be very dangerous, and you should never do that. Whether it happens to fog up inside your car or on the outside, the result is the same.

Before driving, you need to get rid of the condensation. It will well be worth your time – your safety depends on it, after all!

What Should I Do When Car Windows Fog?

We’ll first discuss condensation on the outside of the car glass.

As we’ve already discussed, this happens when the outside temperature is warmer than inside. For example, this will happen on a hot summer day when you’re driving with your AC on.

What you need to do to stop condensation is balance the outside and inside temperatures. This means that you’ll need to warm up the car inside so that its glass will be as warm as the air outside.

Condensation on the Outside of the Car

Let’s look at the steps needed to get rid of condensation on the outside:

  • Turn on your windshield wipers. This will help you get rid of the condensation that has already formed on the outside of the glass.
  • Warm up the inside. This will help prevent more condensation from forming. Turn on your AC and set it on a temperature that matches the outside one. Always remember that you want the inside of the car to be comfortable, not too hot.
  • Turn off the re-circulation button. If there’s a lot of excess moisture in the car, bringing fresh air inside will help to get rid of that moisture.
  • Open the windows. By opening them, the fresh air coming from the outside will create a balance with the air inside.

Condensation on the Inside of the Car

Now, let’s discuss what you’ll need to do when condensation is taking place on the inside. This will happen, for example, on a winter day when you enter your car and turn the engine on.

When you find yourself in such a situation, take the following steps:

  • Turn on the defrost button. You may have to wait for the engine to be warm enough to see any results. The defrost button blows warm air on the glass, and the heating system works to trap water molecules.
  • Turn off the recirculate setting. If you don’t do this step, the moist air inside the car will keep recirculating. To fight condensation, it’s very important to have fresh air from the outside coming in.
  • Crack open the windows. Again, this will help balance out the inside and outside air temperatures, helping to defog. Leaving them cracked for a few minutes will be enough to get the job done.

Just in case your defroster setting button doesn’t work, this doesn’t mean you’re now helpless. If your defrost button doesn’t work, follow these steps instead:

  • Turn on the heat. You want it to be at the highest setting possible, as warm air will help capture moisture. You may have to wait a few minutes to make sure the engine is warm enough. If not, even if you turn on the heat at maximum power, the air will not be hot.
  • Turn on your AC. The moisture will be extracted from the air as the air conditioning cools it down.
  • Turn off recirculation. This will bring cooler air, which is not as moist, into the car from the outside.
  • Crack open the windows. Whether you use the defrost button or not to defrost your windshield, letting fresh, dry air make its way into your car will balance the temperature difference.

Tips to Prevent Your Car Windows From Fogging Up In The Future

The steps we shared so far are useful to solve condensation issues whenever they happen. However, an important question remains: what can you do to prevent your car windows from fogging up again in the future?

There are a few tricks we can use to try to eliminate the source of the problem. Some of these tips may seem strange, but they have stood the test of time and are proven to actually work.

Remove Moisture Sources

The most obvious source of moisture in a car is the driver’s and passenger’s breath.

When we breathe, we produce moisture in the air. Our body heat is also a source of humidity. This is the main reason why car windows usually fog up after we make our way inside a vehicle.

Obviously enough, we can’t stop breathing or control our body heat, but we can eliminate other sources of dampness.

For example, wet towels or shoes after a day at the beach, your gym bag or open drinks can all be taken out of the equation. Check the mats and carpets to make sure they aren’t damp.

Basically, anything that can cause evaporation has to go.

Check for Any Leaks

Is there any water leaking into your car?

The rubber stripping on all doors, windows and sunroofs should always be in good condition to keep the inside of your car well-isolated.

The air conditioner and the sunroof could be another possible source of water leakage.

To be sure about whether or not you have any of these going on, have a professional check all of these for potential leaks.

Clean Your Windows Thoroughly

The water molecules from condensation will bind with any particles of dirt or dust.

So, this means that keeping your car windows spotless inside and out will help to get rid of excess moisture.

You can use a normal window cleaner and microfiber drying towels to finish.

Rubbing alcohol is also known to work wonders to clean glass surfaces. Just make sure you don’t leave any streaks on the glass, as this would only make matters worse.

Regularly Air it Out

Moisture can accumulate in your car after a prolonged period of it not being used.

When the weather is sunny and dry, be sure to leave the fogged up windows open for a few hours. The fresh air that makes its way in will help get rid of any moisture trapped inside your vehicle.

Keep the Air Recirculation Button Off

As we’ve already covered, the more fresh air that circulates in the vehicle, the less moisture will keep forming inside.

So do turn on your AC to blow dry, warm air over the windows, but make sure that air is coming from outside and not recirculating the same air around the cab.

Use Shaving Cream or Anti-Fog Products

If you don’t have commercial anti fog cleaning products, shaving cream works just as well.

Sounds weird, right? I know! But it works perfectly well. Just treat your car windows with it to avoid fogging, and see the results for yourself.

Here’s what to do:

  • Spray a little shaving cream directly on the inside of the foggy window.
  • Use a paper towel to spread it evenly all over the glass.
  • With a clean paper towel, remove excess shaving cream.
  • The window should look clear, with no streaks or residue.
  • Repeat this process on all glass surfaces inside your car.

This easy remedy will help keep the moisture from fogging up the inside. And, you probably will not have to rush to the store to get anti-fog!

Final Thoughts

By now, you know all about what causes car windows to fog up. You now also know all the steps you need to take to solve this problem, whether it happens on the inside or on the outside.

You’re now also equipped with a few peculiar (but very effective) tricks to help you avoid this from happening again in the future, too.

Before we sign off, though, we want to leave you with a curious fact.

Did you ever notice that some car windows fog up while others don’t? Experts believe that much of this is due to their shape, as vertical windows seem to capture less moisture.

That’s why windshields, which are slanted in shape, tend to fog up more – as they collect more water droplets.

Let us know how you managed to stop your car windows from fogging up, in the comments section below! If you have any tips and tricks of your own, ones that other readers might also benefit from, we’d love to hear about them!

Also, feel free to ask us if you have any additional questions to stuff we might not have addressed in this piece. We’ll be sure to answer them!

Kyle Palmer

From childhood go karting and motocross, to collecting and obsessing over scalextric, matchbox and radio controlled cars, I've always had an obsession with cars. Learning through manuals, books, trial and error, and more knowledgeable family members, I've also enjoyed tinkering with the mechanics and electronics of any vehicles I've owned. Now, over 3 decades later, I've started this site as a place for me to share my knowledge, to teach others how to care for and maintain their vehicles themselves, at home, so they can get the most of their vehicles and save a pretty penny compared to always seeking out professional help.

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