The AA has shared the fastest method to clear fog from a car windscreen on cold mornings, recommending a combination of hot and cold air to defog windows quickly.
As winter weather arrives, the motoring organisation advises drivers to switch on the warm air blower and rear windscreen heater alongside the air-conditioning. Allowing some outside air into the car can also help turn a frosted-over vehicle back into something more drivable.
Why Air-Con Helps Prevent Misting
Activating the air-conditioning extracts moisture from the air inside the vehicle, which helps prevent misting. The AA also cautioned against rubbing anything onto windows that could smear them and impair visibility, responding to a hack suggesting half a potato could stop windows steaming up.
"We wouldn't recommend rubbing anything onto your windows that could smear them and impair your ability to see the road clearly," the AA said.
Avoid Smears and Cold Water Risks
Drivers should avoid using their hands to wipe misted-up windows, as this leaves smears. Instead, the AA recommends a lint-free absorbent cloth if necessary, and advises staying with the car while the engine runs until the windscreen clears.
On particularly cold days, the AA warned that water could freeze before it is noticed, and warm water actually freezes more quickly than cold water. If it refreezes, it can form a layer of ice on the windscreen and driveway, accumulate on the wipers and freeze them to the glass, potentially damaging the wiper motor or tearing off the rubber.
"We wouldn't recommend using cold water as it can freeze on the windscreen and cause damage," the AA added. "The best thing to do is follow the steps above on this page. Turn on the car heaters and the air-con, and use a proper brush or de-icer to scrape the frost of your frozen windscreen while you wait for the car to warm up."
