If I don't warm up my car in the mornings the windshield gets so foggy that I can't see.

The Heat/AC doesn't seem to help fast enough, and wiping the windshield leaves streaks.

How can I deal with this quickly so I can get back to driving safely?

  • Surprised this hasn't been mentioned yet.
    – user22124
    Commented Sep 13, 2017 at 8:07

6 Answers 6


Since the fog comes from moisture inside the car a simple solution is to dehumidify the car by filling an old sock with kitty litter and placing it inside the car in an inconspicuous place like under a seat. You might want to use an old pair of socks and double wrap the kitty litter.

Video from Huffington post of the kitty liter trick

But did you know there's a super easy way to beat motor mist?

Simply put some cat litter in a sock, leave it in your car and you'll be on the road without delay every time.

  • 2
    I'm curious if anyone has used this method? It sounds really cool if it works? Any links/stories?
    – Abraxas
    Commented Dec 24, 2014 at 22:02
  • 3
    While this is a good answer, care should be taken in choosing which litter to use. There are many different types of kitty litter; they do not all absorb moisture the same and some are toxic. Silicate dust can cause problems for all, while pregnant women need to be particularly wary of potential birth defects.
    – David Culp
    Commented Dec 25, 2014 at 7:51
  • 1
    Check this too.
    – user22124
    Commented Sep 13, 2017 at 8:07

The fog comes from water condensing on the windshield or windows. The problem is that the air inside the car is warmer and/or wetter than outside. (e.g., https://van.physics.illinois.edu/qa/listing.php?id=1511)

One of the faster ways is to lower your windows to lower the temperature in the car, and decrease the humidity by bringing in outside air. This may not be particularly comfortable but it definitely works.


If wiping leaves streaks, then there is something on the glass (oils from wiping with a rag that isn't perfectly clean etc) so it will not get better until properly cleaned.

You need to really give your windscreen a good clean, and then use a product like Rain-X's window defogger (it's a window cleaner with something else that prevents condensation) - and it will last for months (possibly years - not sure)

Also, using aircon helps to dry out the air in your car, reducing the problem.


Instead of using warm air to defog your windshield, use cold air - it is much faster. Also, instead of putting on the air conditioner, switch it to windshield mode.

  • Hi @WangiPaPa. Some people thought that your answer was short and lacked good content, but I thought that it was a good hack, maybe just not displayed the best. I hope you don't mind that I lengthened it. :)
    – michaelpri
    Commented Mar 9, 2015 at 1:40

Prevent the fog by wiping the window/windshield by a cloth soaked in shampoo water or soap water! This is just a temporary solution but it will be helpful sometimes!


Put a mains powered fan heater in the car for a few minutes before leaving home. (Think about safety risks when doing this.)

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