Set the timer to 125 seconds

How to use the online timer

While the windscreen is warming after an overnight frost, keep your attention on the glass rather than watching the clock. A countdown of one hundred and twenty-five seconds gives the heater time to begin loosening a light icy film while you check that the demister is running and the wipers remain off the frozen surface. Stay with the car and watch how the frost responds.

Because windscreen frost varies with the British weather, the displayed interval is a practical starting point rather than a fixed rule. You can change it directly on the page before starting if the layer looks thicker, the morning is especially cold, or the heater is already blowing warm air. If clear patches appear sooner, stop the countdown and finish checking visibility without waiting for it to expire.

When the glass still has opaque or frozen areas at the end, clear any loosened frost safely and run the same countdown again. A second pass can suit a windscreen that cooled heavily overnight, but check progress between runs instead of leaving the heating unattended. If the first run has already restored a clear view across the whole screen, there is no reason to repeat it.