How To Defog Your Car Windshield in Summer, Winter, and Rain

I’m sure this has happened to all of us – a cold winter morning, you’re rushing to get to work or drive the kids to school. You get inside the car, and you’re probably freezing at this point. You turn the heating on, and in several seconds, the fog starts blurring your vision. There’s no chance you’re driving like this – it’s nearly impossible to see, and it’s not safe.

That’s why it’s essential to learn how to make your windows clear again. In this article, you’ll learn:

  • How to defog your windshield in cold weather?
  • How to defog your windshield when it’s hot outside?
  • How to defog your windshield in the rain without AC?
  • What causes a windshield to fog up?

What Causes a Foggy Windshield?

We have all learned about condensation in school, and fog on a windscreen is a result of just that – moisture condensing on the inside or outside of your windows. Water vapor in the air will naturally cling to any cold surface, whether that’s your windscreen or rear windows. This is what causes them to fog up and obscure your vision.

This phenomenon can occur during both hot and cold months. In the winter, the air outside your vehicle is cold, and typically fogging will start building up inside your automobile. This is due to the presence of moisture inside your car, and it’s coming from the air you’re exhaling or even the snow on your boots.

In hot weather, you can observe the opposite phenomenon – a result of hot, moist air hitting the cooled windshield (if you have the AC turned on).

There is also a third, less common reason for a foggy windshield. Most cars manufactured after the year 2000 have a cabin filter. This great accessory filters out pollutants, pollen, and dust providing you with fresher and cleaner air inside the cabin. It can also be a reason for your car defogger working abnormally. When dirt and debris collect inside the filter, there is less air circulation inside the cabin. As a result, your windshield can become susceptible to fogging.

Finally, another minor contributing factor can be dirt on your windshield. Maintenance is essential, and giving your windshield a clean is not just for aesthetic purposes. Moisture loves dirt and sticks to it like metal to a magnet.

Try to set a reminder for a monthly car wash just in case. If you’re a DIY fan, I can recommend some cheap and efficient homemade windshield washer fluid recipes. Or, if you prefer to play it safe, check out my recommendations of the best commercially sold windshield washer fluid.

So the question is – how to stop your windows from fogging up? Now that we have determined the cause, we can work out a way to quickly defog a windshield.

How to Defog My Car Windshield in Summer?

In the summer months, when the moisture and temperature outside your car are greater than on the inside, you can quickly notice condensation building up on the exterior of your car windows. In order to get rid of it, you need to balance out the air and try to match the inside and outside temperature.

The goal is to get the inside warmer. You probably won’t be thrilled to hear this, but it’s essential if you want to go about your day and drive to a designated location.

Step 1

Since the condensation is happening outside, you can easily use the windshield wipers to get rid of moisture, saving you enough time to level out the temperature inside the cabin. Here are my recommendations on where to buy windshield wipers in case you feel like it’s time for a new pair.

Step 2

The critical thing to focus on is warming up the inside of your car. If you decide to turn on the air-con, you can still do that, but stick to the lowest possible setting, which means the coolest temperature. Still, keep your own comfort in mind. If you don’t see any change in the next few minutes, you might have to sacrifice the air conditioning for a bit and switch it off completely.

Step 3

Finally, I recommend you switch off recirculation. If you don’t know where that is, look for the button with a circular arrow inside an icon of a car. Sometimes the button is simply a circular or semicircular arrow. By switching off this boost, you allow the moisture levels inside and outside your car to level out. This is a common mistake people make when they try to defog their windows as soon as possible.

How to Defog My Car Windshield in Winter?

If you don’t want the inside of your car to turn into a scene from the Titanic, it’s important to follow these steps in order to defog your windows successfully:

Step 1

The fog in the winter will usually form on the inside of the car and windows. Here I would recommend switching on your heating to the highest setting. 

Step 2

Turn the AC on as well. The hot air in the car holds moisture, and the air con can pull that moisture from the air and pass it over the evaporating coils.

Step 3

Once again, I’ll advise you to turn the recirculation button off, and this will allow for dry air to enter inside the cabin. 

Step 4

If you want to aid cold airflow inside the cabin so you can exchange humid air for dry air, the quickest way to do that is to open a couple of windows slightly. You only have to do this for a few minutes. 

Another way of doing this if you don’t want to open up the windows is using the defroster feature (if your car has one). Turn it on and wait for the hot air to evaporate the moisture from your window. Once again, the recirculation needs to be switched off! If you leave this function switched on, the heat inside your car or the air con will reuse the air on the inside instead of pulling dry air from the outside. 

How to Defog Your Windshield in Rain Without AC?

There isn’t an ideal way to get rid of fog on a windshield when it’s raining. Your best bet is to either open the rear side windows slightly and let air in (and rain, unfortunately) or keep a clean cloth and wipe your windows with it to get rid of the moisture. Something you can do in advance is prepping your windows and covering them with some shaving cream, and wiping it off, a simple method I have explained in the section below.   

How to Stop Windows from Fogging up?

There are a few tips and tricks worth noting down if you want to say goodbye to foggy windshields. 

  • Get those windows clean. Many people will advise you to use ammonia-based window cleaners because they’re highly effective. However, I suggest you don’t get those. In fact, look for the opposite. Why? Ammonia can start deteriorating the rubber around your car glass. You can also do a pretty good job choosing any of these DIY windshield washer fluids to clean your windows.
  • A strange yet effective trick is using shaving cream. You can spray some on the inside of your clean window and spread it with a cloth. Using a clean paper towel or toilet paper, remove the shaving cream. It creates a film over the glass, which helps against car windows fogging up.
  • Make it a habit to turn your defroster on as soon as you enter the car. For those of you who have a remote start feature, switch the defroster on about 15 minutes before you go to work, and this should give it enough time to work its magic.
  • If you park your car somewhere safe, like in a garage where you won’t worry about burglars or unwanted animals trespassing, you can leave an open window overnight to keep the fresh air coming in.
  • Entering your car with dry shoes is essential. Try to wipe your shoes with a dry towel so you can get rid of any snow or rain moisture before you get inside your car. This can severely lower the risk of window fogging.
  • Often the problem can be in your heating or ventilation system, making it very difficult to defog windows. If you have tried everything, you might want to get your HVAC checked and stop asking yourself how to get rid of fog on your windshield. A lot of the time, you need an expert’s opinion.