Why does my lock freeze in winter even with a covered door?

Moisture migrates into the cylinder through normal key use and condensation. Once trapped inside, it freezes when temperatures drop. Graphite powder applied before winter — not oil-based sprays — keeps the mechanism moving without trapping water.

My door sticks every summer. Is the lock the problem?

Usually not. Wood doors swell with humidity and push the bolt and latch out of alignment with the strike plate. A locksmith can adjust the strike plate position or plane the door edge — you rarely need a new lock.

How often should exterior locks be serviced in Ontario?

Once a year is a sensible baseline — ideally in early autumn before freeze-up. Commercial doors with higher traffic or exterior exposure benefit from a spring check as well.

Residential Security Updated June 27, 2026

How Canadian Weather Impacts Your Locks and Hardware

By Treco Locksmith & Security · rated 5★ across 205 Google reviews · serving Burlington & Hamilton

Southern Ontario’s climate puts hardware through genuine punishment: below-zero winters, humid summers, rapid shoulder-season swings, and road-salt air near the escarpment. As locksmiths serving Burlington, Hamilton, and the surrounding Halton and Hamilton regions, we diagnose weather-related lock failures year-round. Most are preventable.

Winter: Frozen Cylinders and Sticky Deadbolts

When temperatures drop, moisture trapped inside a cylinder freezes. The result:

Keys won’t insert fully or turn smoothly
Deadbolts feel stiff or catch mid-travel
Padlocks on exterior gates seize overnight

Cold also causes metal to contract slightly, tightening internal tolerances and making an already-worn cylinder feel completely seized.

What to do

Apply graphite powder to the keyway before the first freeze — it lubricates without trapping moisture. Avoid WD-40 and oil-based sprays; they attract dust and turn gummy in cold. If a lock freezes during a cold snap, warm the key with your hand before inserting it rather than applying heat directly to the lock body.

For frozen commercial doors — loading docks, fire exits, steel entry doors — the stakes go beyond inconvenience. A door that won’t open on a cold Monday morning disrupts operations. Our commercial door repair service covers emergency thaw-outs and permanent weatherstripping upgrades that keep commercial steel frames functional through freeze-thaw cycles.

Summer: Humidity, Swelling Doors, and Misaligned Strikes

Southern Ontario summers bring humidity levels that cause wood doors to absorb moisture and expand. The door shifts in the frame, and suddenly the bolt no longer lines up with the strike plate. Signs to watch:

You have to lift or shoulder the door to get the bolt to throw
The latch doesn’t catch on its own when the door closes
Handles feel loose or the door drags along the threshold

The lock itself is almost never the culprit here. Hardware adjustment — repositioning the strike plate, tightening hinge screws, or planing the door edge — typically resolves the problem without replacing anything. Our residential locksmith team handles these adjustments routinely as part of a seasonal tune-up.

Spring and Fall: Rapid Expansion and Contraction

Shoulder seasons in Ontario mean temperature swings of 15°C or more within a single week. Repeated expansion and contraction loosens mounting screws, shifts strike plate alignment, and can cause latches to miss their keep.

What we see most often:

Strike plates that have crept off-centre over years of thermal cycling
Latches that don’t catch consistently in cool mornings but work fine by afternoon
Deadbolt throws that bind at the entry point of the strike

Catching these small misalignments early is far cheaper than dealing with a mechanism that eventually fails or a door that can no longer be secured. For a broader seasonal checklist, see our guide on locksmith tips to keep you secure.

Rust, Corrosion, and Road Salt

Exterior hardware within a few blocks of Hamilton’s arterials or Burlington’s lakeshore picks up road-salt air from November through March. Salt accelerates corrosion on:

Exposed cylinder faces and keyways
Hinge pins and barrel bolts
Strike plate screws and door closer arms

Switching to exterior-rated brass or stainless hardware and keeping a thin coat of graphite on the cylinder significantly extends service life. If finish corrosion is already visible, address it before it reaches the internal mechanism — pitted internal components are grounds for replacement, not just lubrication.

Practical Maintenance Schedule

Season	Priority task
Early autumn	Graphite the keyways; inspect weatherstripping
After first freeze	Check deadbolt operation on all exterior doors
Late spring	Recheck strike plate alignment; adjust swollen doors
Summer	Tighten hinge screws; address any sticking latches

When to Call a Locksmith

Seasonal wear accumulates gradually, which means problems often seem minor until they aren’t. We recommend a professional inspection if:

A deadbolt requires noticeably more force than it used to
A door needs to be lifted or pushed to lock
Visible rust or green oxidation appears on exterior hardware
A key has ever broken off in a frozen cylinder

Treco Locksmith and Security serves Burlington, Hamilton, Oakville, Stoney Creek, and surrounding Halton and Hamilton communities. Call us at (905) 977-8476 or visit our contact page to schedule a hardware inspection before the next season catches you off guard.

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