Windshield Fogs Up When It Rains – What To Do?

Maximum visibility when driving is critical to your safety. This is especially important when driving at night or in the rain. But what if you notice your windshield is fogging up when it's raining? We researched the causes of this inconvenience from several professional sources.

There are several methods for getting rid of windshield fogs caused by rain. What you should do will depend on whether the fog is happening during warm weather or in colder temperatures. They will include:

  • Activating your windshield wipers
  • Turning on your defroster
  • Shutting off your vehicle's air conditioner
  • Avoiding recirculating the air

Now that we know strategies to rid a windshield of fog, we'll break them down so they're easier to understand. You might wonder if you can prevent a window from fogging up beforehand, or why your windshield fogs up in the summer. For answers, read ahead.

Car windshield all fogged up due to cold weather, Windshield Fogs Up When It Rains - What To Do?

Getting Rid of the Windshield Fog - How to Do It?

When you experience windshield fog, it can reduce your visibility greatly when you need it the most. Driving in the rain, especially at night, requires that you can see as much as you can out of your windshield.

So, it's okay to be concerned about this fogging problem. 

Tinted car windshield

Thankfully, there are several methods that work quickly. Try these out the next time when it rains and your window is accumulating moisture.

De-fogging Your Windshield When It's Warm Outside

The key to getting your windshield to defog is to make sure that the interior surface of the glass is as close as possible to the temperature outside.

The windshield wipers will work to remove the fog that builds on the outside. However, your main issue is removing the fog that you see inside the glass.

Turn off the air recirculate button. You don't want the cold air from inside your vehicle to keep the inside of the windshield cold.

Let the outside air in. This will help equalize the temperature differences between the outside and the inside. Aim the vents as close to the interior surface of the windshield as possible.

First, shut the air conditioner off. Next, activate the defroster. This will blow warmer air onto the windshield. The warmer the windshield gets, the faster that fog will go away. 

De-fogging Your Windshield When the Temperatures are Colder

Fogged up windshield during a light rain

In this scenario, the situation is the reverse of the above. It will be substantially warmer inside your vehicle than it is outside of it.

However, you'll use the same principles. Equalizing the temperature outside with the temperature on the interior surface of the glass will make the fog go away.

Activate the air conditioner. This will draw the moisture out of the air. Aim it toward the windshield as best as you can. This will chill the windshield and make the fog disappear.

Turn off the air circulation button. Instead of the warmer air constantly recirculating inside the cabin, allow the colder air from the outside to come in. This will also equalize the temperature of the windshield and make it de-fog.

You can also crack the windows of your car open. You won't need to open them much. An inch will work. This will let the dry, cold outside air mix with the warm, humid air in your vehicle. The result is the windshield ends up losing that fog.

Car owner wiping the car windshield

How to Help Prevent Fogging on the Windshield?

There is a way you can keep the window from fogging up so badly. It might even keep it from fogging up completely. For this to be possible, you'll need to do a little routine preventative maintenance. 

The moisture that accumulates on your windshield is aided by any surface debris on the glass. Bugs, dirt, or any travel film are a magnet for moisture. They give it a base to cling to, and a surface area for it to grow.

If you want to keep the window from fogging up, keep it clean. Scrub it with an approved windshield cleaner, inside and out every time you wash your vehicle. This prevents any moisture from having a place to stick.

Why Does the Windshield Fog Up in the Summer?

Maybe you thought that the only time a window fogs up is during the chilliest months of the year. If that's true, you were probably surprised the first time you noticed fog developing on your vehicle's windshield on a rainy summer day.

There is a scientific reason for this occurrence. When it's hot outside, you tend to either have the windows open or the air conditioner running.

When the windows are open, you won't notice any fogging. But turn the cool air on, and you will notice the inside of your windshield starting to accumulate some moisture.

When there is a big difference in the temperatures outside the vehicle and inside your cabin, condensation will gradually accumulate on the surface of the glass. The humidity that this temperature imbalance creates leads to the window slowly fogging over.

Fogged up windshield inside the car

How Do You Dehumidify a Car?

Under certain conditions, your vehicle will gradually accumulate a good deal of humidity. It might be because of the climate you keep your vehicle in. Or, it's from leaving your windows or sunroof open during a rain.

Either way, it can be a pain to live with. Thankfully, there are some methods you can use to relatively quickly take the humidity out of your car.

To view this car dehumidifier on Amazon, click here.

Turn On the Air Conditioner

For low levels of humidity, run the air conditioner. This will suck the humidity out of the air fairly quickly. While some circumstances will cause it to take a little more effort, this should be the first thing that you try.

Dry Out the Floor Mats and Seats

Next, be sure that the floor mats are dry. If they've gotten wet, odds are the floor's carpeting is wet, too. Shake the floor mats off, and use towels, or a shop vacuum to dry the floor.

Be sure that the seats are dry. If you left the windows open during a storm, there's a great chance that these are wet as well.

The fabric will be slow to release the moisture via evaporation, so you'll need to get to work to dry them out yourself. A shop vacuum comes in handy here, too.

Use a Moisture Absorbing Material

Spilled baking soda on the table

Finally, there are substances you can use to suck the moisture out of the air. Opening several boxes of baking soda and strategically placing them around your vehicle will work to remove the humidity.

Just make sure that you only do this when the vehicle is in park, or they might tip over and create a mess.

You can also get a portable dehumidifier. This will quickly work to remove the most troublesome amounts of moisture that have invaded the interior of your vehicle.

Final Thoughts

Car windshield all fogged up due to cold weather

There are several strategies for getting rid of the fog on the inside or the outside of your windshield. If you want to avoid window fogging before it starts, consider keeping the inside and outside of the glass as clean as possible. Drive safe!

We hope this post on windshields helped answer all of your questions. For additional helpful information, we recommend reading the following automotive posts:

Can Your Car Pass Inspection With A Cracked Windshield?

How To Defog Your Windshield Without Using The Heater

Driving with a Cracked Windshield: Should You Be Doing That?

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