During winter and rainy seasons, fog is common. Fog makes it difficult to see from the foggy windshield. It is not only annoying but can become a safety hazard as well.

What causes fog on the windshield

Regardless of the extreme climate, you must keep the car inside comfortable. It means you can battle with the foggy window. If the extreme climate is cooler, turn the heater on. 

When dealing with cold, you turn on the heater in your car; the fog starts forming. In warmer, humid regions, if you turn on AC, it causes fog-blurring windows from outside. You must adjust the internal and external temperature of your vehicle.

When the weather is cold, the difference between temperature and humidity level of interior and exterior.

When the weather is cold

On colder days, air moisture in your car from the snow on boots and passenger exhaling turns to condensate when it strikes air to the windows next lower the temperature: known as the dew point. The air condensations make your car’s windshield foggy.

In hot weather, the opposite happens when the outside muggy air reaches the dew point after its temperature reduces 

Follow these steps to defog your windows.

Increase AC temperature

Increase your car’s AC temperature. Increasing the car’s internal temperature is the best way to defog your windshield; it blows hot air into the cabin, increasing its interior temperature.

Open your car window a bit

If the humidity outside the car is lower than the car’s cabin, the passengers release excessive moisture and water. It increases the water content inside the car, reducing it with a window opening. It allows the outside air to circulate freely inside the cabin, reduces the dew points and allows removing fog from the windshield. 

Using AC as a dehumidifier

You can use car AC as a dehumidifier. Most modern cars have climate control. The car system allows AC to switch to defrosting. The AC will dehumidify the car interior and then warms it up by blowing warm air. If you set your AC in cooling mode, the air on the windshield results in slow moisture elimination. Remember! Cold air cannot hold more water than warm air.

Using engine temperature

Ensure maintaining engine temperature around 90 degrees Celsius. It allows your windshield to defog properly and quickly. When engine temperature combines with AC temperature, it makes it easier to defog the windshield fast. Don’t wipe off the mist from the windshield because it can make the glass streaky or dirty, making visibility difficult.

Deice the outer side of the window

Defrosting is significant while your windows defog. It is a separate process. You must not include hot water in it. You have to plan a bit; it can save you from larger issues. Make a mixture of rubbing alcohol or isopropyl with water. You can restore this solution in your car and spray it when required. It is the easiest way to defog your windshield.

When it is warm 

When the moisture and temperature outside the car increase, moisture condenses on the windshield. You need to match the car’s interior and exterior. It means you have to keep the temperature at one point. The following are the steps to follow.

First thing: Use wipers on your windshield. It will help eliminate being condensed until you balance the temperature. 

Warm your car: Turn the AC to the least cool settings to increase the temperature without discomfort. You can turn off your AC completely.

Leave recirculation off: it is better to turn off the recirculation of your car AC to fight fog on the windshield and other windows. You can equalize the moisture level of the car and the environment.

When it is raining

Defogging is important when you are driving in the rain. Otherwise, you may have a road accident.

Turn on AC 

Turning on your air conditioner helps remove air moisture from your car.

Turn air recirculation off 

It is the top mistake in defogging the windows.

Defrost your car without heat. 

If the car heater is malfunctioning, you can use the above mentioned solution.  


A foggy windshield can be a reason for accidents. You must know why the fog appears and then rectify the reason. Most modern cars contain a rear defogger button. Turn the rear defogger button on. But for the old cars, you must turn on the AC or open the car windows slightly. It reduces fog on your front and rear windshield.                                         

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How to use windshield defogger?

If your car AC is manual, turn its ventilation flow towards the windshield to match the internal and external temperature. Turn its heating on.

How to defog your car window in a few seconds?

The formula for defogging your car is 2/3 parts isopropyl and 1/3 part water or rubbing alcohol. Pour the formula into a spray bottle. Then spraying it on the windshield helps it to defog in seconds.

How does Defogger work?

It channels warm air through ventilators aiming at your windshield directly. The rear Defogger throws the Electrical currents through black fiber that runs through the rear windshield.

What is a demister or defroster?

A demister, defroster or Defogger is a system to clean up condensation and removes frost from the side windows, rear glass or windshield of a car.

Is Defogger cold or hot?

The warm air from a defogger helps to evaporate moisture near the windshield. It is a temporary fix. It would be best to lower the glass’s temperature to prevent fog from forming.