DETAILED ANSWER · UPVC DOORS AND MECHANISMS
How can changes in weather affect a UPVC door?
Understand common symptoms across cylinders, handles and multipoint locks.
Temperature and moisture can affect materials and the way a door sits in its frame. A door that is already near the edge of its adjustment may feel tighter as conditions change. If a fault appears during a cold or warm spell, note whether it affects the whole door or one locking point.
Do not compensate with force or adjust fire-door hardware. Seasonal changes are not a reason to accept a door that will not secure. If the problem starts with weather, record the conditions and any visible rubbing, then arrange an inspection if it persists.
Avoid shaving, planing or forcing the door because the cause may be an adjustment or hardware issue. A specialist can check the alignment and explain whether adjustment or repair is appropriate.