Use This Method from a Former NASA Engineer to Defog Your Windshield in No Time

Use This Method from a Former NASA Engineer to Defog Your Windshield in No Time
Photo: dies-irae, Shutterstock

One of the more annoying parts of cold weather is all the extra work it means for those who drive. Between putting snow tires on in extreme regions and waiting for your vehicle to warm up, everything takes a little bit longer. There’s also the dreaded feeling of going to start the car and realising the windshield is all fogged up. If you find yourself in this position, it’s not as bad as it seems: a former NASA engineer has shared his science-based defogging technique, designed to get the job done faster. Here’s what to know.

How to quickly defog your windshield

This tip comes to us from Mark Rober, a former NASA engineer and self-described “friend of science.” In a five-minute YouTube video, he walks us through his four-step method for defogging your windshield in half the time. (Note that the title on the still below says he’ll be talking about defrosting windows, but in the actual video, he only addresses defogging.)

In the video, Rober uses the scientific method to test out a variety of techniques, before landing on the one that he found works the best for defogging your windshield and car windows. Here are the steps involved:

  1. Turn your car’s heater on full-blast. Hot air can hold more moisture.
  2. Turn your car’s air conditioning on. According to Rober, this pulls moisture out of the air as the air passes over the AC’s cold coils.
  3. Make sure inside air circulation is off. “Winter air is cold, and we know it doesn’t hold much moisture,” Rober explains. “So if you bring it into your car and heat it up, it has a lot of absorption capacity.”
  4. Crack as many windows as possible — even for a few seconds — to allow for the exchange of the humid car air with the dry cold air outside.

Of course, there are plenty of variables, like the temperature, precipitation and kinds of settings that come with your car, but if you deal with fog a lot, these are worth a shot.


  • So glad for these tips today when it’s almost freezing here. 35 degrees F today – oh, wait no, sorry I forgot I live in Qld. Silly me it was 35 degrees C.

  • So, basically the things every car owner knows to do anyway. Gotcha…
    Of course, if you own an EV, you just hit the preconditioning button on the remote a few mins before you leave and the car is warm by the time you get to it, with windows nicely defogged. Another great reason EVs are better…

  • Don’t need to be an engineer to know this, it’s fairly common knowledge….

    My mum taught me these exact same tips some 25 odd years ago when i was on my L plates.

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