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How to Easily Prevent Vehicle Windows From Fogging

Has your windshield ever fogged up for no apparent reason? You try to act quickly, experimenting with different air temperatures, activating the windshield wipers, and even rolling your windows down, but a simple fix is hard to find.

What causes our windows to fog up? Is there a quick solution that will work every time? 

Below, we answer these questions to equip you with a fool-proof way of solving this issue when it happens. Let’s dig in.

Why Do Vehicle Windows Fog? 

Vehicle windows can fog up for many different reasons. We’ll focus on the main two: humidity and condensation. Foggy windows usually happen when there is a significant difference in temperature outside of your car than inside.

The temperature difference can involve excessive amounts of moisture. The inside of your windshield will typically fog up when it is warmer inside the vehicle than outside. It also happens when the humidity inside the car is high. That is why you experience window fogginess more often when multiple people are inside the vehicle.

Likewise, you’re more likely to experience condensation on the outside of your windshield when the temperature inside your car is cooler than it is outside. We tend to experience excessive condensation during the summer when we’re blasting our A/Cs, or when the humid air hits the cold windshield in the morning.

How Do I Stop My Car Windows From Fogging Up?

If your windows have ever fogged up while you were driving, you’ll know firsthand how scary it can be. It can be incredibly upsetting if you don’t know how to remedy the situation quickly.

What exactly should you do next time this happens?

Pro Tip: The one tool we recommend is this RainX product. It works wonders! All the coming solutions don’t require a product.

Turn On Air Conditioner in the Winter

If the inside of your windshield is foggy when it’s cold outside, humidity is often to blame. The heat from your car’s engine and the moisture from your breath can cause water droplets to form on the cold windshield.

A quick way to combat this problem is by blasting the A/C through your defroster vents. This will neutralize the temperature difference and cause the fog to dissipate quickly.

Turn On Heat in the Summer

If your windshield fogs up due to condensation from the A/C, you can turn on the heat to retain your visibility quickly. By blasting hot air onto your windshield, you’ll cause the moisture droplets to evaporate. This is especially helpful during hot, humid summer days.

Turn Off Recirculating Vents

If you find that your windshield is constantly fogging up no matter what you do, make sure that your vents aren’t recirculating the same air from inside your vehicle.

Try to neutralize the difference in temperature and humidity levels between the inside of your car and the outside air. It might help to allow some fresh, outdoor air to filter in through your vents and rebalance the atmosphere. 

Open Your Windows

A quicker way to neutralize the difference in temperature between the inside of your vehicle and the outside air? Open your windows!

You’ll quickly let out any built-up moisture and flood the interior area of your car with fresh, outside air. This tactic can virtually eliminate window fog.

Use Your Windshield Wipers for Outside Moisture

If you’re dealing with exterior condensation on your windshield, sometimes all you need to do is activate your wipers.

This is especially effective if there is moisture from the morning dew, as it’s less likely to return. However, if you use your windshield wipers to clear the fog and it keeps coming back, we recommend either opening your windows or using your defroster to heat your windshield.

Why Are My Car Windows Fogging Up Inside When Parked?

If you find that your car is fogging up from the inside out when it’s parked, it’s probably because of built-up heat and humidity.

This is most common when a person a pet is sitting in the vehicle for long periods without air movement. It’s caused by heat and moisture meeting the windows’ cold glass. It’s also more likely to happen on colder days. 

How Do You Stop Condensation in a Car?

There are many effective tricks to stop condensation build-up in a car. The best way to combat this problem is to understand the most common causes of windshield fogging. That way, you can know how to dissipate the fog quickly.

A general rule of thumb is: if it’s colder outside than inside the car, blast the A/C; and if it’s colder inside the car than outside, turn on the heat. If the fog keeps coming back, roll down the windows to balance out the heat and humidity levels and then work on maintaining a comfortable temperature inside your car. When in doubt, refer back to this article!

What are your go-to tactics to keep your windshield fog-free? Let us know in the comments below!

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  1. Dave says:

    Easiest way to avoid fogging inside your car is fill a sock with kitty litter, tie the end and keep it in the car. I put one on the dash and no foggy windows.