How to Stop Your Windshield From Fogging Up

foggy windshield

Why Do Windshields Get Foggy?

Windshield fog is created when there is a difference in air temperature and humidity between the inside of the car and the outside. For instance, when it is cold outside, and you get into your car. Your warm body and the moisture coming from your breath and your skin will increase the humidity in the car. When this humid, warm air touches the cold glass, the water in the air condenses on the glass to create fog. This can happen the other way as well. If it is hot and humid outside and you turn on the A/C in your car. Your A/C, simultaneously cooling down and dehumidifying the air, can create fog on the exterior of your glass.

Fastest Way to Get Rid of Windshield Fog

If It’s Cold Outside

  1. Turn on your Defroster, this will blow air up onto the glass.
  2. Turn your heat to high, hot air can hold more moisture and will begin to evaporate the fog on the windshield.
  3. Turn on the A/C, the air passing over the coils will dry out the air rebalancing the humidity
  4. Turn off recirculation, you want to pull in the colder, dryer air from outside
  5. If you can bear it, crack your windows to expedite the rebalancing of humidity and temperature

If It’s Warm Outside

  1. Turn on your windshield wipers to squeegee off the excess moisture
  2. Turn the A/C to as low a setting as you can bear
  3. Turn off recirculation, you want to pull in the hotter, more humid air from outside
  4. Crack the windows to expedite the rebalancing of humidity and temperature

How do Anti-Fog Treatments Work?

Anti-Fog treatments were originally created for NASA. They needed something to clear the fog off of astronauts’ space suits while they were on spacewalks. As they say, necessity is the mother of invention! But how do Anti-Fog treatments actually work? Well, they traditionally work using two different methods.


This is a common chemical used in many different applications, but for anti-fog, it works by lower the surface tension of water. Surface tension is what causes water to attract to itself and become droplets. By lowering surface tension water no longer tries to form big droplets but instead stays as a very thin film across the glass which doesn’t impair vision.

Hydrophilic Coatings

Hydrophilic coatings work in much the same way as a surfactant. Hydrophilic means “water-loving” so this coating actually attracts water. By using this the water, instead of forming big droplets, has a tendency to be pulled flat into a sheet against the glass. In this way, it is much less likely to impair vision as it forms a very thin clear layer of water.

Tips for Applying an Anti-Fog Coating

  1. Make sure that your glass is clean so that your coating will stick easily and last longer. A good Glass Cleaner can be found here.
  2. Make sure that you apply these coatings only to the inside of your vehicle’s windows. These are not meant for exterior use.
  3. All of these anti-fog coatings are safe for use on the interior window’s tint.
  4. Make sure that you apply a good even coating to the whole windshield using a clean dry cloth

Best Products to Reduce Windshield Fog

No matter what you do if you live in extreme climates then you’re going to encounter windshield fog. Fortunately, there are a few products out there that when applied to your car’s glass can both, reduce fog accumulation, and the amount of time it takes to dissipate. We tested these products to see what were the top contenders in each category. These are the products we found to be the best.


Best Overall

Optix 55 Fog Gone

The best overall windshield anti-fog treatment is Optix 55 Fog Gone. This anti-fog spray works fast, providing immediate results. You just rub the product on, wipe it off, and you are good to go. Unlike most of its competitors, it is natural and hypoallergenic. Fog Gone is safe for skin and eyes so you can rest easy knowing that it isn’t harming you or the environment.

Additionally, it is effective on many different materials like Polarized, UV, Iridium, Photo-chromatic, Polycarbonate, Lexan, and many more. Don’t let fogged-up mirrors and glass put you in danger on the road. Get Optix 55 Fog Gone and drive safely.

Best Anti-Fog Windshield Spray

Rain-X Anti-Fog Treatment

A very close second in this category comes from a major brand and expert on everything that has to do with automotive glass. That is Rain-X Anti-Fog. Rain-X makes a windshield fog treatment that is meant to go on the inside of your car’s windshield. They make no claim about how long you can expect this to last but the bottle is small enough to store away in your vehicle for easy application when necessary.

If too much is applied to the windshield and a haze appears a little water can be applied to clean the glass back to crystal clear. This one is simple, easy, and backed by a pretty major player in the game. So you can trust that it’s been through some rigorous quality control.

Best Anti-Fog Treatment

 Invisible Glass Anti Fog Spray

From a brand that I like quite a bit comes Invisible Glass Anti Fog. Another great addition to what is, unfortunately, a relatively small market of anti-fog products. This product is made in the USA and works surprisingly well at keeping fog off of the windows and mirrors.

It dries to a streak-free shine and comes with a 100% satisfaction guarantee. Either you are satisfied or you get your money back. So for no risk, this is definitely a product worth giving a shot.

Best Anti-Fog Film

Frienda 12 piece Anti Fog Nano Coating Car Film

If you want a more long term solution that won’t require you to reapply the treatment to your windshield every few weeks then you can try an anti-fog film. The Frienda 12 piece Anti Fog Nano Coating Car Film comes with everything you need to begin seeing clearly. It comes with cleaners and cloths to prep the area along with 12 pre-cut adhesive films. These films are nano-coated to disperse water in the rain and prevent fog. Ensuring that you can see clearly no matter what the weather.

These coatings are easy to apply to the rearview mirror, side mirrors, or passenger windows. When used on the rearview or side mirrors they can also reduce some of the glare from oncoming vehicle headlights at night. These do not seem to work as well as some of the coatings that you apply by hand. But if you are needing a permanent solution or you just don’t want to have to apply any coatings, then these offer another simple solution.

Best Anti-Fog Wipes

Medpride Pre-moistened anti-fog lens wipes

If you want something a little more portable and convenient, or perhaps something you can leave in a couple of different cars. Then these anti-fog wipes work perfectly. Your best option, in this case, would be Medpride Premoistened Lens Wipes. They work perfectly on any glass from reading glasses, to motorcycle helmets, to car glass.

These wipes come in a box with 200 pre-sealed wipes and come very highly rated. That way you can disperse them as needed between cars, or bags, or in the house for electronics. Without ever having to worry about running out.

Best Anti-Fog & Glass Cleaner

Rain-X Glass Cleaner and Anti-Fog Wipes

The Medpride Premoistened Lens Wipes are our best anti-fog wipes and yes they will clean your glass as well. But they are going to be more useful as a light anti-fog applicator to an already clean windshield. If you’re trying to actively clean your glass and apply an anti-fog coating at the same time then you need Rain-X Glass Cleaner and Anti-Fog Wipes.

These are a much bigger sheet and will make cleaning something like an entire car windshield a much quicker and easier task. They work to instantly eliminate windshield fog or steam as well as removing smoke residue. They will also leave a streak-free crystal clear shine all with one wipe.