How to Clear an Iced Windscreen Safely

How we research

The safe way to clear an iced windscreen is to start with the wipers off, warm the glass from inside, scrape and de-ice the outside while you wait, and not drive off until all the glass is clear. This guide sets out the steps in order, what to avoid and the rules that apply, using UK motoring and government sources. It is guidance, not legal advice.

Last updated: 19 October 2026

Step by step

  1. Check the wipers are off. The AA says to make sure the wipers are not on before you start the car, because wipers frozen to the glass can damage the motor or tear the rubber [1][2][3].
  2. Start the engine and turn on the heating. The AA says to aim the warm air blower at the windscreen and use the rear window heater and heated mirrors if fitted. It also says to run the air conditioning, because it removes the moisture that causes misting [1].
  3. Stay with the car. The AA says to stay with the car the whole time the engine is running [1]. See the rules below.
  4. Clear the outside while the inside warms up. The AA says to use a scraper and de-icer on the outside of the glass [1]. Arnold Clark says to spray de-icer first, because it can help melt the ice faster, and then scrape off what remains [3]. Rias says to take care along the edges of the windows to avoid damaging seals, and suggests gloves [2].
  5. Brush off snow. The AA says to brush all snow off the car, use a soft brush on the front grille and check that the lights are clean and working [1]. Arnold Clark says to clear the roof, because snow left there can slide down the windscreen when you brake [3].
  6. Deal with mist on the inside. The AA says not to wipe misted windows with your hands, and to use a lint-free cloth instead [1].
  7. Check before you move. The AA says not to drive off until all the glass is clear [1]. Highway Code rule 229 says you must be able to see, so clear all snow and ice from all your windows, and also to make sure the mirrors are clear, the windows demisted thoroughly, and lights and number plates clean and legible [4].

What not to do

  • Hot or lukewarm water. The AA says not to use it. Temperature changes can crack glass, especially if it is already chipped, and warm water can refreeze [1]. Rias also warns that boiling water can crack glass [2].
  • Cold water. The AA says it can freeze on the windscreen and cause damage [1].
  • Wipers on a frozen screen. The AA, Rias and Arnold Clark all warn that frozen wipers can be damaged or torn if they move [1][2][3]. Rias also says not to use the wipers to clear ice [2].
  • Online hacks. The AA does not recommend hot water in a sandwich bag or rubbing a potato on the glass, and says anything smeared on the glass can impair your view [1].
  • Clearing a small gap. The AA says clearing only a small “porthole” is risky and could lead to police action for driving dangerously [1].

The rules

  • Visibility. Highway Code rule 229 says you must be able to see, so clear all snow and ice from all your windows [4]. The AA says driving with obscured vision can bring a £100 fine and 3 points on your licence [1]. Check the current penalty before relying on it.
  • Leaving the engine running. Regulation 107 says you must not leave a motor vehicle on a road not attended by a person licensed to drive it unless the engine is stopped and any required parking brake is set. The exceptions listed are for emergency service and certain work uses, not for defrosting [5].
  • Theft. The AA says thieves target unattended cars with the engine running, which it calls “frosting”. It says insurers may not cover theft where keys were left in an unattended car, and that if you go indoors you should switch off and lock the car [1].

Stopping it happening again

The AA suggests parking in a garage if you have one, or on the drive close to the house, and putting cardboard over the windscreen [1].

Questions people ask

How long does it take to clear a windscreen?

None of the sources we opened give a time. The AA says only not to drive off until all the glass is clear [1].

Can I pour water on it?

No. The AA says not to use hot, warm or cold water, and gives reasons for each [1].

Do I need a de-icer or is a scraper enough?

The AA and Arnold Clark describe using both together [1][3]. They do not say a scraper alone will not work.

Is it illegal to leave the engine running while I wait?

On a road, regulation 107 prohibits leaving a vehicle unattended with the engine running [5]. The AA advises staying with the car [1]. Check the rules for private land with the landowner and your insurer.

Sources

  1. How to defrost a car windscreen: step-by-step guide, The AA, theaa.com. The page shows no date. Checked 19 October 2026.
  2. How to de-ice your car windscreen, Rias, rias.co.uk. Dated 10 December 2023. Checked 19 October 2026.
  3. How to de-ice a windscreen quickly and safely, Arnold Clark Autoparts, arnoldclarkautoparts.com. Dated 12 November 2025. Checked 19 October 2026.
  4. The Highway Code: Driving in adverse weather conditions (226 to 237), GOV.UK, gov.uk. Checked 19 October 2026.
  5. The Road Vehicles (Construction and Use) Regulations 1986, regulation 107, legislation.gov.uk. Checked 19 October 2026.