How to prevent your car from fogging up

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3 min read

When winter hits you want to be prepared. (Top tip: get that Christmas shopping done ASAP!) But along with the wooly scarves and cold weather comes some challenges for drivers. Ice and snow is one thing to look out for, but one of the most common, everyday issues is foggy windows.

The chance that your windows will fog up increases during the winter. It can be annoying, sure, but it’s also a significant safety hazard. If fog reduces your visibility when driving, you’ll have to stop your vehicle to deal with it. Please don’t drive blind!

Let’s take a look at the problem in more depth—and what you can do to solve it.

why do car windows fog up?

Ready for some elementary school science? Car windows fog up due to condensation that forms on the interior of glass windscreens. It’s caused by the temperature difference in the inside and outside of the car.

So when warm air generated by the passengers (from breathing, sweating, or having damp clothes) hits the cold glass, it condenses, causing moisture to collect on the windows—and that dreaded fog to emerge.

how to defog car windows (or stop them fogging up in the first place)

open the windows

This is the quickest, low-key fog fix. Roll down the windows and let the air inside the car cool down to stop it condensing. This solution isn’t great for passengers (especially if it's really cold outside) so it's best reserved for those times when you’re driving and you need to improve your visibility fast.

turn up the heating

If you want your passengers to be happy (and who doesn't, right?) then the more comfortable way to defog those windows is to use your car defroster—which will heat up the windshield, and turn up the heating to help evaporate all the moisture collecting on the glass (here’s some more science for you—hot air holds more moisture than cold air!). Don’t use the recirculate setting though—you want the car to pull in dry air from outside.

keep your windows clean

Condensation collects more readily on dirty windows. If you keep your windshield clean (and let it dry it properly after), you will reduce the chance of fog forming.

use anti-fog spray

These products are designed to reduce the chance of fogging. When you spray them on your windshield it leaves a thin layer of film that reduces the impact of condensation on visibility, and increases the speed at which the moisture is re-evaporated.

Winter can be a risky time for driving, so don’t let foggy windows make it any harder. If your car is too far gone to make the most of these de-fogging tips—the heater is bust, the windows don’t work, or the windshield is cracked—then you might be thinking about buying a new car altogether (maybe one with some inbuilt anti-fog tech).

Sell your old car to Peddle and we’ll help you get some extra bucks to put towards a new ride with anti-foggers.