How to Stop Your Windscreen from Fogging Up

Few things are more irritating, or downright dangerous, than a windscreen that fogs up the moment the weather turns. Whether you're dashing off on a cold morning or navigating a rainy drive home, a steamed up screen ruins visibility and ramps up stress.

The good news? It’s easy to fix once you understand what’s causing it, and how to keep it from happening in the first place.

Here’s everything you need to know to stop your windscreen fogging up, the proper way, without reaching for your sleeve or cracking the window like it’s 1995.

Contact us to report infringement.

What Causes Windscreen Fogging?

Fogging happens when moisture inside your car condenses on the cold surface of the windscreen. It’s the same science behind a bathroom mirror steaming up after a hot shower, warm, moist air meets a cool surface and condenses.

Inside your car, this moisture can come from:

• Wet shoes, coats, and umbrellas

• Breathing (especially with passengers in the car)

• Spilled drinks

• Leaking seals or poor ventilation

During colder months, it’s especially bad, as your breath and damp clothes fill the cabin with moisture while the glass stays icy cold.

Quick Fixes That Actually Work

Let’s start with how to clear the fog when it’s already there. These tips are workshop approved and faster than wiping with your jumper.

1. Use Your Demister Properly

Hit that front demist button and set the blower to high. If your car has climate control, use the auto setting. Don’t blast heat straight away; start with cool air to stop more moisture from condensing, then switch to warm as it clears.

2. Air Con Is Your Friend

Even in winter, your air conditioning helps. It removes moisture from the air, so switch it on with the demister. It’ll dry the cabin out much quicker.

3. Open Your Windows (Just a Crack)

If your windows are really fogged and your demister's taking its sweet time, crack the windows for a minute or two. This helps exchange humid cabin air for drier air outside.

4. Keep a Microfibre Cloth Handy

Always store one in your glovebox or door pocket. If things get really bad, use it to wipe the glass clean. Avoid kitchen roll or your sleeve, they leave streaks and fibres behind, making it worse next time.

Long Term Solutions to Prevent Fogging

Stopping windscreen fog before it starts is about controlling moisture. Here’s how to win the war.

1. Check for Leaks

Moisture from leaks around doors, sunroofs or window seals is a major culprit. Check carpets for damp patches, especially in footwells and under mats. If you find any, sort the leak before anything else.

2. Use a Dehumidifier Bag

Cheap, effective and dead simple. These small beanbag style devices soak up excess moisture in your car. Pop one on the dashboard or under a seat and swap it every couple of months. Some are reusable; just stick them in the microwave to dry them out.

3. Don’t Leave Wet Items in the Car

That soggy coat or gym bag? It’s steaming up your glass while you sleep. Always remove damp items when you park up.

4. Clean Your Windscreen, Inside and Out

A dirty windscreen fogs up faster and holds moisture longer. Use a dedicated glass cleaner and microfibre cloth to clean both sides of the glass every week or so. A good trick: add a small drop of shaving foam to the inside, buff it off, it leaves a protective film that helps resist fogging.

5. Replace the Cabin Filter

The cabin (or pollen) filter helps regulate airflow and trap moisture. If it's clogged or old, it can cause misting issues. Change it once a year, or more if you drive in dusty or damp conditions.

6. Keep Your Car Ventilated

When parked at home, crack a window if it’s safe to do so. This lets moist air escape. Better still, park in a garage if you’ve got one, it reduces temperature extremes that cause condensation.

What About Anti Fog Sprays?

They can work, but it depends on the brand and how clean your screen is before you apply it. Some leave streaks, while others wear off quickly. If you’re going to use one, apply sparingly and follow the instructions to the letter.

Workshop tip: Use a separate cloth for application and buffing.

Should You Upgrade Your Demister?

If you drive an older car and your demister barely wheezes into action, it might be worth having it checked. Blower motors, heater cores, or even a failing thermostat can all reduce its efficiency. Mechanics can quickly spot if something’s not working right.

Heated windscreens, common on newer Fords and some VWs, are fantastic, but if you don’t have one, you can still make your existing system perform like new with proper upkeep.

Final Thoughts

If your windscreen fogs up regularly, don’t ignore it. It’s not just annoying, it’s a hazard. Poor visibility is a top cause of winter accidents, and fogged glass is avoidable with the right habits and kit.

Keep your car dry, your air flowing, and your glass clean. Do that, and you’ll spend less time demisting and more time driving.

Stay safe, stay clear, and if in doubt, give your local garage a ring.

Mike Floyd

Senior Maintenance Editor, Car Care Column