Why is My Car’s Windshield Fogged Up in Summer?

Windshield fogging is a common issue for many car owners, especially during summer. It can be frustrating and even dangerous while driving. If you’re wondering, “Why is my car’s windshield fogged up in summer?” this article will provide you with the answers and some helpful tips to prevent it.

The Science Behind Windshield Fogging

Windshield fogging occurs when air with different temperatures meets on the windshield. In summer, hot air from outside hits the cool windshield, causing condensation and fogging. On the other hand, in winter, warm air inside the car meets the cold windshield, resulting in the same effect.

How to Prevent Windshield Fogging in Summer

Here are some simple and effective ways to prevent your windshield from fogging up during summer:

  1. Crack Down Your Windows: Roll down your car’s windows slightly (about half an inch) to allow fresh air from outside to enter the car. This will help prevent the windshields from steaming up. However, be cautious when parking in unsafe areas.
  2. Clean the Windshield with Shaving Cream: Apply a layer of shaving cream to your windshield using a soft cloth and then wipe it off with a dry rag. The cream will create a barrier against steam on the windshields.
  3. Apply Potato Starch to the Windshield: Rub a cut potato on your windshield and then wipe off the juice with a clean, soft rag. The sugars and starch in the potato will serve as a repellant against fog build-up on your windshield.

How to Fix a Foggy Windshield in Summer

If you failed to implement the preventive measures mentioned above, here are some recommendations to help you clear a foggy windshield during summer:

  1. Engage the Windshield Wipers: Turn on the windshield wipers and regulate them to wipe across the windshield slowly to clear off the fog thoroughly.
  2. Turn Down the Air Conditioning System: Lower the air conditioning system to match the temperature outside.
  3. Roll Down Your Car’s Windows: Allow the warm air from outside to enter the car, which will help clear the fog from the windshield.
  4. Engage Your HVAC System’s Fresh Air Setting: Most modern cars have a heating, ventilation, and air conditioning system (HVAC) with a fresh air mode. Engaging this mode will open a unique air duct in the vehicle’s front area and allow the direct inflow of fresh air instead of the normal air conditioning cooling air.
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  1. How do you defog your windshield in hot weather?
  • Crack the windows open and allow the inflow of fresh air to naturally defog the car’s windshield. Alternatively, turn on the heater in your HVAC system and increase it to maximum (defroster). The hot air from the HVAC system’s vents will heat and vaporize the moisture on the windshield.

2. Do you use hot or cold air to defog windows?

  • Hot air is best to help defog your vehicle’s windshield. Cold air or low temperatures easily collect moisture to form fog on windshields. So, reversing the temperature is the best way to defog the windows.

3. How do you stop condensation on the inside of car windows?

  • Blasting hot air from your car’s heater will help stop the condensation on the inside of the window. Regulate the HVAC system and turn on the heater. The warm air from the system will heat up the windows and clear off the water vapor in a moment.


In conclusion, understanding the causes of windshield fogging and implementing the preventive measures mentioned above can help you maintain a clear and safe view while driving during summer. Remember, prevention is always better than cure.

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