December 8th, 2021 by Sarah Miles

All motorists know that it’s advisable to be in your car a good 10 minutes before you really need to leave during the winter so that you have time to demist the windscreen on a cold morning. That said, how many of us actually remember to do this? It can be incredibly frustrating sitting there waiting when you have somewhere to be (and driving while peering through a tiny gap in the fog is both dangerous and illegal).

Therefore, as we head into winter, it’s useful to have a few strategies to stop windows fogging up and reduce some of that morning stress.

What causes car windows to steam up?

To understand how to deal with steamy windows, it’s useful to understand why it happens. The simple answer is condensation. As warm, moist air created by your breath and body heat, as well as any additional moisture in the car, hits the cold glass of the windscreen, it instantly cools. When air rapidly cools like this, a lot of the moisture that it holds is pulled out of the air, causing condensation to appear on the window. Naturally, the more moisture there is in the air, the more severe the condensation will be. While you can’t do a lot about the temperature (at least initially), there are a few things you can do to reduce the amount of moisture in the air.

Preventing windows from steaming up

There are a few things you can actually do to help minimise the formation of steam before you even get in the car. They include the following:

Keep windows clean

Particles of dirt give water something to cling to. Very clean surfaces will therefore steam up less.

Create a protective barrier on the glass

You can create a barrier on the interior surface of the glass that helps to prevent water from beading. This could be a specific anti-fog car spray, but you can also do the job with simple shaving foam! The detergent in the foam achieves the same result. Wipe over with a cloth and then buff off with a clean cloth.

Keep the car as dry as possible

Anything that adds moisture will compound the issue. Wet umbrellas, coats, dog towels, and open drinks should all be removed from the car.

Use a dehumidifier

A dehumidifier is something that absorbs moisture from the air. Dehumidifier packs that use silica gel will do this but so will a sock filled with cat litter – yes really! Simply leave them in the car and replace them monthly over winter.

Demisting windows quickly

The following strategies can be used to eradicate steamed up windows quickly:

Open your windows

Ventilating the car the old fashioned way will allow the moist, warm air to escape, although a climate control setting can also achieve the same if your car has one.

Blower high, heat low

Obviously, your most useful tool for dealing with steamed up windscreens is your car’s heater but there is a knack to getting good results: put the blower on full but keep the temperature low. Blasting the glass with hot, moist air won’t really help, in fact, it could make it worse. Slowly increase the heat as the steam clears to warm the glass up.

Aircon on

If you have air conditioning, turn it on to dry the air but don’t turn on the recirculation setting as this will just move warm around the car.

Don’t wipe

Whatever you do, don’t be tempted to just wipe the steam away with a cloth or, even worse, your hand. If you haven’t reduced the heat and moisture in the air, it will just steam up again and you’re likely to smear and mark the glass which can impact visibility even further.