How to defog car windows
5 minute read Published on Apr 3, 2025 by BrokerLink Communications
If you live somewhere with cold winters—like the harsh winters we get here in Canada —you probably crank up the heater in your car to stay warm. But all that warmth can lead to one annoying problem: foggy windows. And let’s be real: driving safely means having a clear view. So, keeping your windows from fogging up can be tricky when there's moisture inside your car. Wondering how to tackle it? Let’s find out.
Quickly defogging your car windows
The quickest way to defog car windows depends on where the condensation is: inside or outside. We will explore both in detail below:
Inside condensation
The fastest way to clear up your foggy windshield or rear window during the cold weather is by switching to defog/defrost mode. It automatically turns on the air conditioning and cranks up the fan to blast warm, dry air onto the windshield—and usually the front side windows, too. Not only does it help melt snow and ice on the glass, but it also clears up that annoying condensation inside. Once your visibility is back, you can lower the fan to keep things quieter.
Car air conditioning is your secret weapon. Sure, cold air might be the last thing you want in the middle of winter, but here’s the trick: it’s not about the chill—it’s about dehumidifying the more humid air inside your car. That’s why it’s called “air conditioning.” You can still set the temperature to something cozy while letting the vents blow out dry, warm air to keep those windows clear.
Also, if your car’s ventilation system has an air recirculation button, make sure it’s turned off. When it’s on, your car keeps reusing the humid air inside instead of bringing in fresh, dry air from outside—which isn’t great if you’re trying to clear up those foggy windows.
Outside condensation
But what about in the summer? On a hot, humid day, the muggy hot air outside can fog up your windshield or windows when they cool down from the inside air conditioning. In this case, the fastest way to clear them is to turn on your windshield wipers or roll down your windows. This will take away the outside condensation and give you a clear view of the roads again.
However, if you keep your air conditioning turned on full blast, your windows will just quickly fog bag up again. You'll want to try turning the air conditioning to its lowest, least cool setting to warm things up a bit without making it uncomfortable. If that doesn’t do the trick, go ahead and turn the air conditioning off completely, then roll down your windows to let in some fresh air and enjoy the breeze.
Why do car windows fog up?
It all comes down to temperature and moisture. On a cold day, the moisture inside your car—like the water from passengers breathing or snow melting off your boots—turns into condensation when it touches the cooler air near your windows. That’s because the air hits something called the dew point, and that condensation is what makes your windows fog up. On the other hand, on a hot, humid day, the muggy air outside can lead to a fogged-up windshield when it cools down from your car's air conditioning.
How to prevent your windows from fogging up
Now that you know how to tackle foggy windows, let’s talk about how to prevent windows from fogging up in the first place. Here are some simple tips that can help make a big difference:
Put baking soda in your car
Baking soda is a natural dehumidifier, which means it’s great for soaking up moisture in the air and helping prevent foggy windows. Just fill a small jar with baking soda, pop off the lid, and leave it in your car.
Put cat litter in your car
Just like baking soda, cat litter designed to absorb moisture can help keep foggy windows at bay. Look for non-clumping or crystal-based cat litter—it works best. Once you’ve got it, pour some into a small container with holes in the lid or even an old pair of socks, and place it in your car. It’ll help soak up the moisture inside and keep your windshield and windows clear.
Apply an anti-fog solution
You can find all kinds of anti-fog solutions out there, either online or at your local auto parts store. They usually come in a spray bottle, making them super easy to use. Just spray it onto your windshield and wipe it off with a clean cloth. These solutions work by using special chemicals that stop moisture from condensing on your windshield, keeping it nice and clear.
Wipe your windshield with vinegar
No defogging solution? No problem! White vinegar can do the trick. Grab a clean cloth and soak it in vinegar, then wipe down your windshield. The fog will clear up in no time. You can also mix vinegar with water for a gentler, diluted solution. Just make sure to use a lint-free cloth to avoid leaving any streaks behind.
Keep your windows clean
It might sound simple, but keeping the inside of your car's windows clean can actually help prevent fogging. The dirtier the glass, the easier it is for condensation to build up. So, take a little time now and then to clean your windshield and windows—it makes it much harder for fog to stick around!
Learn more with BrokerLink
Whether the fog is inside or outside, not being able to see clearly in every direction is a big safety risk. That’s why it’s so important to know how to keep your windows clear, no matter what the weather throws at you. Having clear windows means you’re less likely to end up in an accident, which can help keep your rates lower and avoid costly claims.
Of course, accidents can still happen, and that’s where car insurance comes in. If an accident damages your car, having the right coverage can help with the repair costs. A few types of auto insurance that could be helpful include:
- Liability car insurance
- Accident benefits coverage
- Collision car coverage
- Comprehensive car coverage
- Accident forgiveness coverage
To learn more about car insurance, contact BrokerLink today. You can reach us by phone, email, or in person at any one of our locations throughout Canada. No matter how you choose to get in touch, a BrokerLink insurance advisor will be happy to assist you. We also encourage you to take advantage of our free online quote tool that can provide you with a competitive quote in minutes.