When possible, park in a garage or covered parking to reduce the risk of frozen locks.
How to Prevent a Lock From Freezing. Forget winter wonderland. When winter strikes, it means scraping ice off windshields and driving through blowing snow and on icy roads, or freezing while you wait for the defroster and heater to work. What you never anticipate is that your lock will freeze you out of your vehicle. Yet this happens every year to people living in freezing temperatures. Follow these steps to prevent a lock from freezing.
Make friends with a lock lubricant like WD-40. Spray liberally on all door and trunk locks before the weather freezes. Use the little straw that comes with these cans to spray the lubricant in your keyholes. If faced with a long winter, you may need to reapply WD-40 later in the season.
Try graphite on locks if you can't tolerate the smell of WD-40. Graphite can keep locks in working order when little moisture is in the air.
Store de-icer where it's easily accessible. Part of the problem with buying de-icer is that people keep it inside cars where it does no good on frozen locks. Keep a small can of de-icer in your purse, house or desk drawer at work.
Keep moisture out of keyholes. Some people theorize that it's the freezing moisture inside the keyhole that causes the problem. Try covering the keyhole with putty when the car sits outdoors. Take off the putty when you need to unlock your door.
Heat the end of a key with a match or lighter, and then insert it in the lock.
Avoid pouring hot water on your lock, all the experts say. But if nothing else works, try it and be prepared to work fast because hot water refreezes very quickly.
Cover other locks affected by freezing weather, such as padlocks on sheds or gates. Place duct tape over the keyhole and a plastic bag over the entire lock.