The first thing you probably want to do when you get into the car on a cold winter’s night is crank up the heat. Every time we do this, our windows get fogged up, reducing our visibility. Sometimes, window fog doesn’t have a clear cause, making it downright dangerous for you to be out on the road.
Thankfully, there are reasons for this fogginess, and plenty of ways to counteract it and make your driving clear and fog-free.
Know the Reason for Window Fog
Fog can come from a lot of situations, but the cause is always the same. Fog, or condensation, happens when the inside of your car is warmer than the air outside. That’s why you usually don’t see window fog in the summertime.
Foggy windows are also caused by differences in humidity. Windows will defog when the glass gets warm enough to balance between the inside temperature and humidity and that of the outside, but there are ways to reduce the likelihood that your car will fog up from the get-go.
Keep Your Vehicle Interior Dry

Having anything wet inside the car, including open drink cans, will increase the likeliness that your windows will fog. If you want to stop window fog at the source, don’t get into your car with any wet items of clothing, and avoid making the floorboards of your car or the seats wet with your shoes, umbrellas, or anything else.
Keep Your A/C on Defrost
Leaving your temperature settings on high heat, defrost, and A/C will allow the glass to start equalizing with the outside from the first seconds you start your vehicle. Make sure your recirculate air function is also turned off. Depending on the difference between the temperature inside and outside, your glass may never fog because you will have regulated the temperature before it even got the chance.
Crack Your Windows
If you’re not comfortable doing this while you’re not in your car, leave your windows cracked for a few minutes before you start driving. It might be cold, but it’ll help the temperature and humidity match before you start pumping heat into the cabin, reducing the fogginess of your windshield.
Apply an Anti-Fog Treatment
There are lots of sprays and coatings on the market that, when applied properly, will not allow moisture to accumulate on your glass, leaving your windows fog-free. Applying these treatments is fairly intuitive and the effects will usually last quite a while, meaning most of your winter will be taken care of if you apply it at the beginning of the season.
Use Dehumidifiers
Lots of products on the market are designed to remove humidity by simply sitting in your car. Silica packets, similar to those placed in your shoes or bags upon purchase, can be placed in unobtrusive places in your vehicle. Silica will help to absorb the moisture in the air, leaving you free to heat your car as much and as quickly as you like.
When it comes to window fog, there are thankfully many ways to beat the problem before it even starts. Follow these tips, and your winter will go by fog-free.
If you’ve got bigger problems than fog this winter, check out our services. We can fix your auto glass chips, cracks, and shatters. We know auto glass, and we know we can help you.