The Fastest Way to Defrost Your Car Windows

A car with frosted windshield and windows

Running out to your car in the nick of time only to discover frosted and fogged up window glass is not a fun way to start the day. Lucky for you, we’ve got a few tips on how for fighting that fog and frost and getting you back on your way fast.

Why Can’t You Beat This Winter Worry?

Hot air holds more moisture than cold air, thus when temperatures drop, moisture that was easily suspended in warmer air is released, resulting in condensation - all those little water droplets fogging up your windshield. Former NASA engineer and YouTube enthusiast Mark Rober has an amazing video explaining this, and the defogging process. As the video explains, to defog the fastest, you need to create the optimal environment to aid the moisture removal process.  

Defog & Defrost Car Windows Fast with These Science-Based Tips

  1. Turn your heater on.
    Start your engine, and using the defroster setting, crank the heater up all the way to absorb excess moisture within your vehicle. Remember: Hot air can hold more moisture.
  2. Press the A/C button.
    This may sound counterintuitive to the whole heater thing, but really what you’re doing is activating a setting on your car’s A/C system that helps dry the air within the cab faster with the help of the coils in your A/C system.
  3. Turn air recirculation off.
    You need fresh air to enter the car as well. Winter air is cold, and as it does not hold much moisture, it is dry. Bringing it into your car ups absorption capacity to more quickly dry the saturated air trapped within. 
  4. Crack your windows.
    This helps exchange the humid air in your car with dryer outside air, speeding up the process.
  5. Defrost Windows.
    While the above defogging action is taking place, de-frost your windows. This is an entirely separate process that should NEVER (EVER) include hot water. Defrosting quickly takes a minor amount of pre-planning, but saves a snow-capped mountain of headache later. If you can’t stand scraping, put together a simple solution of 2/3 cup Isopropyl or rubbing alcohol and 1/3 cup water, pouring the mixture into a spray bottle. This solution will not freeze (rubbing alcohol has a freezing point of 138 degrees below freezing), and can be stored easily in your car, allowing you to easily spray away windshield ice wherever you’re stranded.

Defog Your Windshield When It's Raining

  1. Turn on your air conditioner.
    Pressing the A/C button engages the help of the system’s coils in removing moisture from the air.
  2. Turn air recirculation off.
    This is the number one mistake people make when trying to rapidly defog windows.

Defrost Car Windows Without Heat

If you don’t have heat, don’t worry, it’s still possible to defrost your car windows fast with the handy de-icing solution described in Step 5, above.  Need help with your HVAC system inside your home? We know professionals that can help. 

Looking for a clearer path to sparkling, clear glass? Fight the rising fog with the help of Glass Doctor today. Did you know? Glass Doctor is a Neighborly brand. Discover an entire network of professionals to assist with any of your home service needs at