How To Defog Windshield In Summer? (7 Best Ways)

Although many people don’t know it, windshields can also fog during the summer. This mainly happens due to the big difference between the outside and inside temperatures in the vehicle. Driving with a fogged windshield is very dangerous, so it is important to know how to quickly and effectively solve this issue. In this article, we’ll talk about how you can defog your windshields during the summer months. So, let’s start!

How to Defog Windshield in Summer? To defog windshield on your vehicle, turn on the heat and the A/C system simultaneously, wait a few minutes, and the fog will disappear. You can also use Rain-X or shaving foam to defog the windshield. By opening windows and cleaning your windshield, you will prevent future fogging.

The problem with the fogged windshield often appears in the early morning hours. This is especially the case if it is a situation where you have to leave the camp park area in a hurry due to a sudden rain or flood. In the next lines, find out how to act in such situations and what you can do to avoid this.

What Causes Windshield Fog?

Foggy windshields on your RV are caused by the difference in outside and inside temperatures. If you have slept at least once in your vehicle with closed windows, you must have noticed how all the glass surfaces were fogged up in the morning. This is caused by breathing. What can also cause windshield fog inside an RV is showering and cooking.

Windshield fog can be caused from the outside and inside. When the windshield is fogged from the outside, the reason is usually the use of the AC system inside the vehicle.

However, this problem is easily solved by activating the wipers. It is a much bigger trouble when the windshield fogs up from the inside. Read the next chapter to learn how to defog windshields from the inside during summer.

If you have this problem during winter, be sure to read How to Stop Car Windows From Fogging Up in Winter.

7 Ways to Prevent Windshield Fog During Summer

In the summer, the windshield will fog when the humidity and temperature are higher outside than inside the vehicle. This often happens when people enter the RV, close the windows, and turn on the AC. This is what campers usually do on hot summer nights.

If you woke up in your RV after a full night of sleeping under the air conditioner, your RV’s windshield would be fogged. Need to start your vehicle urgently? Just raise the temperature and moisture level inside your vehicle. Here’s how you can do it:

1. Turn On the Heat and A/C At The Same Time

A great way to quickly defog the windshield in an RV is to simultaneously turn the AC unit and heating system on full blast.

This way, the temperatures on both sides of the windshield will soon equalize, and the fog will disappear. This will happen because the AC unit will reduce the air humidity in the vehicle, and the heating system will raise the temperatures and help condensation dripping to evaporate.

2. Reduce Moisture Level

One way to prevent windshield fogging is to adjust your behavior while staying in the RV. This can be done by preventing the unnecessary formation of moisture in the air.

Maybe you can’t avoid cooking dinner in the RV when it’s raining outside, but you can avoid leaving wet towels inside the vehicle. Also, after each shower, be sure to vent your RV.

Related article: How to Get Ice Off Windshield? 8 Best Ways

3. Clean Your Windows Regularly

When the windshield is cleaned, it won’t fog up so easily. That means that the windshield should be cleaned regularly to avoid fogging. When there is dust, pollen, traces of bird droppings, or any other dirt on the glass surfaces, they will fog up much faster because the moisture clings to the dirt.

4. Activate Fresh Air Setting

When the windshield fogs up in the summer, and this has not happened before, there is a possibility that someone is wrong with the air ventilation settings in your vehicle and sets the system to circulate the air inside the vehicle.

To avoid windshield fogging, you need to adjust the ventilation so that the system draws fresh air from the outside into the RV.

On the RV control panel, there is a button regulating the air intake, which has a car drawing with a circular arrow inside. If that button is ON, simply deactivate it, and your windshield will be defogged after a few minutes.

5. Use Rain-X

If you often have a problem with a fogged windshield during the summer on your vehicle, then you should think about other solutions to prevent it. Coat the windshield with a hydrophobic agent. A good recommendation is to use Rain-X, which has excellent reviews.

6. Use Shaving Foam

If you think Rain-X is too expensive for your budget, don’t worry; there is another way to defog a windshield. By using shaving foam! Of course, shaving foam is not as easy to apply as Rain-X, but if you want to save money, go ahead.

How to coat the windshield with shaving foam?

First, clean the windshield well. Then spray out a small amount of shaving cream, and spread it by hand on the glass. Wait for 2 to 3 minutes, then wipe off the foam with a dry cloth. That’s it. After a few minutes, your RV windshield will not fog up because it will be too smooth.

7. Open Windows On Your Vehicle

If the weather conditions allow it, i.e. if it is not raining outside or there is a strong wind blowing, you can quickly and easily defog the windshield by opening all the windows in the RV.

As we have already mentioned, the windshield gets fogged due to the temperature difference on the outside and inside of the vehicle. If you open the windows, the temperature will balance out, and the fog will disappear.

Want to learn more? Be sure to watch this video.

Main Reasons Why Windshields Fog Up in Summer

Although many people do not understand how fogging of windshields can occur during the summer, it is possible. In this chapter, we’ll cover all the main reasons why this happens. Here’s what causes an RV windshield to fog up:

1. High Moisture Level

In the summer, the windshield will easily fog up when the vehicle’s interior is cooled with the help of the AC system. The air from the AC system is dry and cold, and the air outside the vehicle is usually warm and humid in summer. When these two different states of air collide on the windshield, fogging occurs.

2. Wet Clothes Inside the Vehicle

Humidity is the main reason why windshields fog up in the summer. One of the most common is casually leaving towels and wet clothes all over the vehicle.

Evaporating moisture from textiles is often the cause of windshield fog. If you have the problem of windshield fogging up, and until now you haven’t been careful where you leave wet clothes, start paying attention.

3. Rain

When it rains during the summer, the inside of the windshield easily fogs up because rain usually causes a sudden temperature change. Just as the temperature change when day turns to night can fog up the windshield, the same happens when we are surprised by a summer shower while camping.

4. Difference Between Outside and Inside Temperature  

Also, it is the difference in temperature that leads to this problem. The windshield will fog up quickly when it is colder inside the vehicle than outside.

Campers often need to close themselves in the RV at least at night in the summer to escape the heat. But this means that the interior of the vehicle will be colder for a long time than the temperature outside the vehicle, which will cause fogging.

5. Air-Recycling Setting Is Activated

If the windshield in your RV gets fogged up, there is a possibility that you have turned on the air-Recycling setting.

When the same air moves inside the vehicle, it gets very moist, and the windshield fogs up quickly. Instead of the recirculate option, activate the standard fan with fresh air from outside. 

Many campers use the air recirculation option in the summer to avoid excessive amounts of pollen in the RV, especially if the RV is parked in the wild. However, if windshield fogging is a bigger problem for you than pollen, change this habit.

6. Sleeping In A Vehicle

One of the most common reasons why the windshield can fog up in your vehicle during the night is sleeping. Studies have shown that a person, when it sleeps, it expels an average of 65 ml of water each hour.

Imagine two people sleeping in an RV all night with the windows closed. When you add this up, you’ll see how much moisture in the air can be raised just by sleeping. Therefore, you should have good ventilation in the RV, especially at night.

7. When Windows Are Left Down

If it is a very hot day, fogging of the windshield can be caused by the partially open windows in the RV during the night. When the temperature starts to drop, condensation and fog occur. It is a good idea to open the windows in the RV only after the air has cooled.

Related article: Why Put Bags Over Car Mirrors When Traveling Alone?

8. Park Your Vehicle In the Garage

Whenever you have the chance, park your vehicle in the garage in the summer. Although this will be a little more difficult for RVs that are much larger. The vehicle is in the garage under controlled conditions, and the differences in temperature and humidity are not so extreme.

Final Thoughts

Driving with a fogged windshield is dangerous, and it is important to defog it before hitting the road. In this article, we’ll cover the main reasons why windshield fogs up and how to prevent it.

In the summer months, the windshield gets fogged up from the inside, most often because campers try to keep the interior of the vehicle comfortably cool.

Also, the windshield will fog up faster if the surface is dirty. You can do this by manipulating the flow of hot and cold air, but with the help of several tips and tricks, we have mentioned in this article. Try them out, and let us know which helped you the most.