As the weather gets colder, it can cause your locks to freeze.
Frozen locks are the result of moisture accumulating by the strike or inside the lockset. The moisture could be from a recent rainstorm, snowfall, or even humidity from the warmer months that never fully dried out. When the temperature drops below zero, the trapped moisture freezes and causes the lock to seize and the hardware will not work properly.
If your lock is frozen, spray the seized latch bolt by the strike with an automotive brake cleaner; you only need a spray or two. The brake cleaner removes the moisture and dries out the latch bolt. To finish the job, spray the latch bolt with a light coating of silicone spray to seal it and prevent further moisture from accumulating and freezing again.
Another way to prevent freezing for all your locksets is to regularly lubricate the cylinders with powdered graphite. This will help drive out moisture all year long. Do not use WD40 or other liquids because they can actually lead to more dirt collection within the lock’s cylinder and lead to more problems.