Symptoms
- Key won't turn or insert fully in cold weather
- Lock worked fine before a cold snap
- Feels like something is physically blocking the lock
Likely causes
- CommonMoisture inside the lock cylinder freezingCondensation or rain that gets into the lock can freeze solid in cold temperatures.
- PossibleIce buildup around the latch or bolt itselfIce can form around the edges of the door and bolt, not just inside the lock.
- PossibleExisting dirt or old lubricant thickening in the coldOld grease-based lubricants can stiffen significantly in freezing temperatures.
What to do
- Warm your key with a lighter or matches for a few seconds (being careful not to overheat it), then insert it and gently try turning it.
- Alternatively, apply a hand warmer or hair dryer directly to the lock cylinder itself for a minute or two.
- Once thawed, spray a de-icing lock lubricant or straight rubbing alcohol into the keyhole to help clear remaining moisture.
- Avoid forcing the key if it won't turn, since a bent or broken key in a frozen lock is a bigger problem.
- After thawing, dry lubricate the lock with graphite or PTFE spray to help prevent refreezing.
- For a persistent problem, consider a weatherproof lock cover for winter.
Tools and parts
- Lighter or hand warmer
- De-icing lock lubricant
Lock de-icer spraySearch: “lock de-icer spray”
Dry lock lubricantSearch: “graphite lock lubricant”
When to call a pro
Call a locksmith if you can't safely warm or thaw the lock, or if forcing a stuck key has bent or broken it off inside.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.