How to Demist a Car on Rainy Days

To quickly demist your car on rainy days, start by turning on the air conditioning and setting it to the windscreen vents. The AC removes moisture from the air, speeding up the process. Set the temperature to warm, as hot air holds more moisture and helps clear the glass faster. Turn on the rear windscreen heater if your car has one.

For best results, follow these steps:

1. Turn on the ignition and start the engine.
2. Set the fan to maximum and direct airflow to the windscreen.
3. Engage the air conditioning (even in winter) to dehumidify the air.
4. Adjust the temperature to warm, not hot, to avoid fogging up again.
5. Use the recirculation mode only briefly, as fresh air helps reduce moisture buildup.

If the mist persists, check for leaks in door seals or a clogged cabin filter. Keeping a microfiber cloth in the car can help wipe away minor condensation. Models like the Ford Focus and Vauxhall Corsa often have efficient demisting systems, but the technique works for most vehicles.

A mechanic’s tip: Prevent mist before it forms. Before rainy weather, apply an anti-fog treatment to the inside of your windscreen. Products like Rain-X Anti-Fog create a hydrophobic layer, reducing condensation. Pair this with regular maintenance—clean windows free of grease and check cabin filters. A clogged filter traps moisture, worsening misting issues. Simple upkeep keeps demisting quick and effective.

1. One-touch demisting. After starting the vehicle, locate the one-touch demisting button on the dashboard, typically marked with a fan symbol featuring three curved lines. Press it to activate the demisting mode for the windscreen. Once demisting is complete, press the button again to turn off the mode.
2. Air conditioning demisting. In summer, turn on the car's air conditioning, press the one-touch demisting button, then set the fan speed to maximum, activate the A/C button, and adjust the temperature to the lowest setting for quicker mist dissipation. In winter, wait for the engine to warm up for a few minutes before turning on the heating, set the fan speed to maximum, and then engage the one-touch demisting mode for effective mist removal.
3. Open the windows. Opening the windows allows air to circulate, reducing the temperature difference between the inside and outside of the car, which naturally dissipates the mist.
4. Use a demisting spray. Apply the spray to the misted windows and wipe clean with a dry cloth. This effectively removes mist and helps prevent its recurrence in the short term.
5. Apply washing-up liquid. You can make a homemade solution by diluting washing-up liquid with water and spraying it onto the misted glass. The principle is similar to that of commercial demisting sprays.
6. Wipe with a cloth. Simply wiping the mist off the glass with a cloth is a straightforward method, but ensure this is done when the vehicle is stationary, as doing so while driving significantly compromises safety.

During rainy or foggy conditions, it is advisable to activate the car's external air circulation function to maintain airflow between the inside and outside of the vehicle, effectively preventing mist formation.

However, avoid keeping the external circulation on continuously. For instance, when driving through particularly dusty areas or in heavy traffic, switch to internal circulation to prevent the car's air from becoming polluted by external conditions.