How to De-Ice a Windscreen Safely (and What Not to Do)

A frozen windscreen is a daily nuisance in winter. Clearing it properly matters for safety, and doing it the wrong way can damage the glass. Here is what works.

The quick, safe method

1. Start the engine and turn on the demister. Set the heat to a moderate level, direct the air at the screen, and switch on the rear screen heater.
2. Use a plastic ice scraper on the outside of the glass. Scrape from the centre outwards.
3. Use de-icer spray for stubborn ice. It melts ice quickly and costs little.
4. Clear the wipers. If they are frozen to the glass, free them before you switch them on, or you risk burning out the motor.
5. Clear all the glass, including side windows, rear window and mirrors.

What not to do

• Do not pour hot water on the screen. The sudden change in temperature can crack the glass. Even lukewarm water can refreeze into a sheet of ice.
• Do not use a metal scraper or a credit card that could scratch the glass. A proper plastic scraper is cheap.
• Do not drive with only a small peephole cleared. You must be able to see properly all round. Driving with an obstructed view can lead to a fine and points on your licence.
• Do not leave the car running unattended. It invites theft, and your insurer may not pay out if the car is stolen with the keys in or the engine running. It also wastes fuel. See cold starts, short trips and idling.

Do you need to warm the engine first?

Modern engines do not need a long warm-up. Once the glass is clear, drive away gently. The engine warms up faster under light load than when idling, and you use less fuel. Avoid hard acceleration until the temperature gauge rises.

How to stop it freezing

• Park facing east, if you can, so the morning sun reaches the windscreen.
• Use a windscreen cover or a sheet of cardboard under the wipers on frosty nights.
• Park in a garage or sheltered spot where possible.
• Wipe condensation off the inside before you leave the car, and leave a window slightly open only if it is safe to do so. Damp air inside is what freezes on the glass.
• Apply a rain repellent or an anti-ice treatment. Some drivers find these help, but results vary, so treat them as a bonus.

Misted windows inside

Use the demister and air conditioning together. The air conditioning removes moisture from the air, which helps clear the glass faster. Turn off the recirculation setting so fresh, drier air comes in.

Be ready in the morning

Allow five to ten minutes on frosty mornings so you are not tempted to drive away before the glass is clear. For a full list of winter preparation, see our winter car checklist. If you are planning a longer trip, compare fuel prices near you before you set off.