How to Remove Fog from a Car Windshield

Co-authored by Ed Beery

Last Updated: January 6, 2023

Fog gathers on your windshield when air of different temperatures meet. This means fog in the summer is caused when the hot air outside hits your cool windshield. Winter fog gathers when the warm air in your car meets your cold windshield. Understanding how the fog is created can help you get rid of it depending on the season. You can also take steps to prevent your windshield from fogging, saving yourself some time.

Method 1

Method 1 of 3:

Removing Fog from Your Windshield in Hot Weather

1
Turn down the AC if it’s warm outside. If you’ve got foggy windows in the summer, turn down your air conditioner. This will warm up your car and get the inside air temperature to match the outside a bit better. You can also open your windows a bit to allow more outside air in (and it prevents your car from becoming too stifling).^{[1]
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2
Turn on your windshield wipers. If the fog is on the outside of your windshield (as it will be during the summer), you can remove it with your windshield wipers.^{[2]
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Expert Source

Ed Beery
Automotive Specialist
Expert Interview. 19 November 2021.} Simply turn them on to their lowest setting and let them run until the fog is gone.^{[3]
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3
Open your windows. This is a quick way to get the temperature inside your car to match the temperature outside. Roll down your windows as far as you can so that the warm air outside gets into the cool interior of your car.^{[4]
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Expert Source

Ed Beery
Automotive Specialist
Expert Interview. 19 November 2021.}

Method 2

Method 2 of 3:

Removing Fog from Your Windshield in Cold Weather

1
Change your air source. Most cars come equipped with buttons that allow you to recirculate the air already in your car or to pull air in from outside. If your windshield is fogging, change the setting so the air gets pulled into the car from the outside. Look for the button that has a little car with an arrow pointing inside the car. Tap this so the light above it is on. ^{[5]
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- Alternatively, tap the button with a car and circular arrow inside of it so the light goes off. This turns off the function that recirculates the air already inside of your car.^{[6]
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  Expert Source
  
  Ed Beery
  Automotive Specialist
  Expert Interview. 19 November 2021.}
2
Lower the temperature in your car. Because fog is caused by differing air temperatures, getting the air temperature inside your car to match the air outside will reduce fog. Turn your car fans on the highest setting.^{[7]
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Expert Source

Ed Beery
Automotive Specialist
Expert Interview. 19 November 2021.} And turn the air temperature down as cold as you can stand.^{[8]
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- This is the fastest method but also the coldest, so be prepared to shiver a bit!
3
Turn on the defrost vent with cool air. The defrost vent will direct air straight at your windshield, but the cool air will help your windshield temperature match the air temperature outside. This can help get rid of the fog on your windshield.^{[9]
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Method 3

Method 3 of 3:

Preventing Fog on Your Windshield

1
Use silica cat litter. Fill a sock with silica cat litter. Tie off the end with a piece of string, and then place one or two full socks near the front of your dashboard. This should absorb the moisture inside your car over night, preventing any fog buildup.^{[10]
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2
Apply shaving cream to your windshield. Use the type of shaving cream that foams up when you squirt it out of the can or bottle. Spray a small amount of cream onto a soft cotton cloth and spread it over your entire windshield. Use a clean, dry rag to wipe it off. This should create a moisture barrier on your window, preventing fog build up.^{[11]
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3
Roll your windows down if you can. If your car is in a secure area, roll your windows down about a half inch or so. This allows some outside air to get in to the car, and can prevent the windshield from fogging.^{[12]
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- This method is best for the summer time, since you don’t want to risk any ice or snow getting into your car during the winter.

Expert Q&A

Question

What causes fog on inside of windshield?

Ed Beery
Automotive Specialist
Ed Beery is an Automotive Specialist and the Owner of InTechgrity Automotive Excellence based in Denver, Colorado. With more than eight years of experience, he specializes in providing maintenance and repair services for both individuals and companies. Ed and the InTechgrity Automotive Excellence Team are approved by the American Automobile Association (AAA) for repairs and are Automotive Service Excellence (ASE) certified.

Ed Beery

Automotive Specialist

Expert Answer

The fog on a windshield is condensation that occurs when moisture condenses on the warmer side of a surface—in this case, your windshield. The temperature difference determines which side of the windshield the condensation collects on.
Question

How do I stop my car windows from fogging up?

Ed Beery
Automotive Specialist
Ed Beery is an Automotive Specialist and the Owner of InTechgrity Automotive Excellence based in Denver, Colorado. With more than eight years of experience, he specializes in providing maintenance and repair services for both individuals and companies. Ed and the InTechgrity Automotive Excellence Team are approved by the American Automobile Association (AAA) for repairs and are Automotive Service Excellence (ASE) certified.

Ed Beery

Automotive Specialist

Expert Answer

You can keep your car windows from fogging up by keeping a window open about an inch or so to allow outside air in and prevent fog from building up. Don't do this if the outside temperature is colder than the inside of your car (especially if the outdoor temperature is at or below freezing).
Question

How do I remove the fog best when neither my A/C nor heat works? Also, my windows leak, allowing rain in and building up more moisture.

Ty_097

Community Answer

To remove fog/moisture, get a room temperature cloth and wipe the inside of the windows with it. If your windows leak, get a window screen cover (the ones you normally use to stop frost) and put that on.

Warnings

Do not ever reach outside of your car while it’s in motion to clear off your windshield. If you have to wipe it off and your windshield wipers won’t do it, pull over and put your car in park.

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