Aaron Widmar
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Cursed Condensation! How Can I Defog My Windshield & Windows?

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Few things are worse than being late for work, starting your car, and not being able to drive because of that INFURIATING, FOGGY WINDSHIELD! It never fails to screw you over on your worst days and no matter what you do, doesn’t clear up. You’re just stuck on the side of the road with your hazard lights on.

You’re probably here wondering, “How can I defog my windshield and windows?” We’re here with the answers to why condensation accumulates on your windows and what the best correction methods are.

Tackling the Problem of Having Wet, Foggy Windows on Your Car

Foggy Windshield and windows defog my windshield

How are you supposed to be able to see through your windshield like this?!?!?!
Photo: Antony Theobald via CC

Why Do I Have Foggy Windows?

Generally, foggy windows happen because of the difference in temperature and moisture between the inside and outside of your car.

During the cold seasons, the air outside is brisk and dry, while your presence inside gives off heat and humidity (think of that moist breath against the cold glass). Warm food, wet clothes, hot bodies (yeah, you know what we’re talking about) all can emit balmy moisture.

According to Mike Hoppe, automotive climate control systems engineer, “In its simplest form, it’s too much water in the air, and it condenses on the glass…It condenses on the inside because the outside is colder, and when it’s colder outside that lowers the relative humidity point.”

This can be especially difficult to correct if your windows struggle to warm up due to poor insulation.


Sheep Lamb Foggy Windshield and windows defog my windshiel

Even animals can generate heat that fogs up windows!
Photo: SplitShire via Pixabay

How Can I Defog my Windshield and Windows?

Some vehicles these days come with climate control and fog sensors that will correct any condensation issues automatically, but most of us aren’t so lucky. If you have an older car suffering from hazy visibility, he’s how you can tackle the issue.

In the Cold: If you want to clear your windshield rapidly, drop the inside temperature and humidity to match the outside. Turn on the A/C or defrost without heat and/or open up the windows to dissipate moisture. You can wipe the inside if you want, but that will leave streaks and won’t accomplish much in the long run.

For a better solution that takes time, turn on all defrosters and up the heat. This will warm up the glass and adjust the relative humidity, which is most important.

In the Heat: This situation is essentially the opposite and can happen during hot, wet seasons. If condensation forms on the outside of your windshield, don’t blast your A/C! Roll down your windows, put the heat on low, and use your wipers to keep your visibility clear.

New Air: In either situation, don’t recirculate your air! You want fresh air to come in rather than the old recycled air that was causing the problem. Keeping the same humid or cold air inside will just perpetuate the dilemma.

Wash Up: Keep your windows clean. A spotless windshield is less likely to become foggy than a grimy one–and will fog up far less.