A change in feel has several possible causes
Timber can move when its moisture content changes, so a seasonal change in how a timber door closes is possible. The British Woodworking Federation describes moisture-related movement in timber doors; that does not diagnose every sticking door or explain faults in uPVC. Worn hinges, a shifted frame or a mechanism problem can produce similar symptoms.
Note the door material, when the symptom appears, and whether it affects the latch, handle, key or closing gap. Record any pattern after rain or a change in dampness, but do not treat timing as proof of the cause. Do not leave a door unsecured while waiting to see whether the symptom changes.
Avoid improvised adjustments
Turning hinge screws or moving keeps without knowing the door system can affect alignment, seals and locking-point engagement. Do not force a handle or use a spray lubricant without checking the manufacturer's instructions for that exact product. Some manufacturers warn against particular substances or methods.
If the door is a fire door or part of a communal building, seek the responsible person's advice before making changes. A door that will not close or latch correctly may affect more than convenience. Report the symptom and any visible damage promptly.
Give a repairer useful context
Describe the timeline, the door material, what the handle and key do, and whether it still locks. Take a wide photograph and a close view of the relevant edge or frame, avoiding key cuts and personal details. RapidLock lists uPVC door and window repairs; ask whether your particular fault is within the current service scope.
If a fault persists or worsens, see the uPVC door diagnosis guide for safe observations. It cannot confirm the cause remotely.
Sources and further reading
These sources support the general guidance above. Standards may change; check the issuing body for current editions and product scope.