Every year, in the first properly cold week, the calls change. Locks that were fine in March stop turning in June. Here is what is actually happening, why it is almost never sudden, and what to do about it before it happens. Reading about a lock that seizes in the first cold week assumes you have time; the locksmith near me page assumes you do not.
Cold, dry air makes worn locks feel dramatically worse. A little maintenance goes a long way.
Dry graphite
Not oil — oil traps dust. Dry graphite lubricates cleanly.
Realign strike plates
Doors shrink and swell seasonally. A quick strike-plate adjustment saves the lock.
Cover exposed padlocks
A cheap silicone cover doubles their winter life.
Three things happen at once
The first is the lubricant. Whatever is inside a mechanism thickens as the temperature drops, and a lock that was marginal in warm weather becomes genuinely stiff on a cold morning. On a mechanism that has never been serviced, what is inside is often not lubricant at all any more — it is a paste of old oil and years of dust, and that behaves considerably worse in the cold.
The second is moisture. Water that has found its way into a mechanism through a cracked cover, a worn escutcheon or a keyway that faces the weather does not do much in summer. In winter it sits inside a cold metal body overnight and the mechanism seizes. This is the failure that feels sudden and is not: the water got in weeks or months earlier.
The third is the building. Timber shrinks in dry cold and swells in wet heat, and doors move accordingly. A door that fitted its frame reasonably in February may bind against the keeper in July, which produces a bolt that will not throw cleanly and a household convinced the lock has failed when the lock is perfectly healthy.
Why it is almost never sudden
A lock that seizes on a cold morning had been telling somebody for months. It needed a slightly firmer turn in April. It wanted the key jiggled in May. By June the household had a technique and had stopped noticing they were using it. Cold did not break the mechanism; it removed the last of the margin that the technique had been compensating for.
The same is true of the moisture route. A cracked cover on a gate lock, a split housing, an escutcheon that has worn away from the door — those are visible for a season before they cause a failure, and none of them looks urgent at the time because the lock still works. The damage and the symptom are separated by months, which is why nobody connects them.
That gap is the whole reason this is preventable. There is no version of this failure that gives no warning; there are only warnings nobody acted on, because a lock that works with a bit of effort is a lock that works. Recognising the effort as a symptom rather than a quirk is most of the solution. As a Randburg locksmith, a lock that seizes in the first cold week is something we are called to more weeks than not.
What to do when it will not turn
Do not force it. A key that will not turn under normal pressure will not turn under abnormal pressure either, and what happens instead is that the blade twists and eventually snaps — leaving a fragment in the mechanism and converting a stiff lock into an extraction job. This is by a wide margin the most expensive mistake available on a cold morning.
Do not pour hot water over it, either. It works for about four minutes and then you have added water to a cold mechanism, which is precisely the condition that caused the problem. On a really cold morning it can freeze again worse than it started, and you will have moved the failure from inconvenient to complete.
Try the other keys, gently, because a worn blade needs more margin than a fresh one and cold has just removed the margin. If a spare turns when the everyday key does not, the mechanism is fine and the key has worn — which is useful information and the cheapest possible outcome. If nothing turns, stop and ring somebody rather than escalating.
The gates suffer first
Anything outdoors gets all three problems more severely. A gate mechanism collects dust and grit all year, faces driven rain into a keyway designed for water to fall past, and sits in the open overnight when the temperature drops furthest. It is entirely normal for the house to be fine and every gate on a property to be stiff on the same morning.
Exposure makes it worse in a predictable geography. Properties on high ground and open aspects — the ridge suburbs, anywhere without shelter — get more wind, more direct sun degrading covers and housings through the year, and colder nights. Households in sheltered streets a few hundred metres lower genuinely have an easier time of it. The related reading is how to tell if a lock needs replacing, which goes further into the detail.
Which means gates deserve the pre-winter check even where the house doors are behaving. Ten minutes in late summer, once the hail season has passed, catches cracked covers and standing water while they are still trivial. That is a small lock repair item at that point and a seized mechanism plus a call-out three months later.
Lubricant: less than you think, and the right kind
The instinct when a lock stiffens is to spray something into it generously. That instinct is responsible for a good share of the seized mechanisms we open. Heavy oils and general-purpose sprays attract dust and grit, and within a couple of years the mechanism contains an abrasive paste that behaves far worse in the cold than a dry lock would have.
What is wanted is a light, appropriate lubricant, used sparingly, on a mechanism that is otherwise clean. On anything outdoors that has been in service for years, the useful job is usually cleaning first and lubricating second — because adding product to a mechanism full of grit just distributes the grit more evenly.
It is also worth resisting the annual ritual of spraying everything on the property in May. Once a mechanism has been treated correctly it does not need doing again for a long time, and doing it repeatedly is actively harmful. If a lock needs lubricating every winter, something else is wrong with it and that is the thing to deal with.
The pre-winter check
Late summer, once the hail has passed and before the cold sets in, spend ten minutes on the property. Work every external mechanism through its full travel several times and note anything that is stiffer than it was. Look at every cover and escutcheon for cracks. Check whether any keyway holds water after rain. Push each door gently while locked to see whether it moves against the frame.
Anything that turns up is cheap at that point and awkward in July. A cracked cover is a small part; the same crack after three months of rain is a mechanism that has to be stripped and dried and may not recover. A door binding slightly is an adjustment; the same door in a wet winter is a lockout.
Do it at the same time each year and attach it to something you already do — the first weekend after the last storm, the same day the gutters get cleared. The whole point is that it happens without anybody deciding to do it, because the failure this prevents is entirely predictable and almost nobody prevents it. We have written about how to choose a locksmith at greater length elsewhere on the site.
When it is genuinely the end
Some mechanisms do not come back from a winter. A lock that has held moisture through a cold month can be stripped, dried and cleaned and still be finished — corrosion inside the body does not reverse, and a mechanism that has been through that will fail again, usually without warning, at some point over the following year.
In that situation replacement is the honest answer, and it should be quoted as its own decision with the reason stated. What should not happen is a mechanism being condemned because it is stiff on a cold morning, which is a different matter entirely and frequently cures with a clean and a correct lubricant.
If it does need replacing, it is worth choosing for the position rather than the price. An outdoor fitting exposed to sun, dust and driven rain is a consumable if it is chosen as an indoor part, and a long-term item if it is chosen properly. That is a modest difference in cost and a large one in how often you read a page like this.
The ten minutes in late summer that prevent all of it
Once the hail season has passed and before the cold properly sets in, work every external mechanism on the property through its full travel several times and note anything stiffer than it was last year. Look at every cover and escutcheon for cracks. Check whether any keyway holds water after rain. Push each door gently while it is locked to feel whether it moves against the frame.
Everything that turns up at that point is cheap and trivial. A cracked cover is a small part; the same crack after three months of rain is a mechanism that has to be stripped and dried and may not recover. A door binding slightly is an adjustment; the same door in a wet winter is a lockout on the coldest morning of the year with somebody already late.
Attach it to something you already do so it happens without anybody deciding to — the first weekend after the last storm, or the day the gutters get cleared. The failure this prevents is entirely predictable, gives months of warning and is still the single most common reason we are called out in June. Most of it is small lock repair work done at the right time of year.