Why does my door stick in summer but not in winter?

Timber absorbs moisture from the air and expands, then releases it and contracts. In humid summer conditions a door can grow enough to bind in its frame, and in dry winter air it shrinks back and closes freely. The effect is seasonal and reversible, which is why the problem appears to come and go.

Because it is seasonal, the important advice is to resist planing the door at the worst point of the year. Removing material while it is at maximum swell leaves a visible gap in winter when it contracts, and that gap is permanent.

Before adjusting anything, check the hinges. Screws loosen over time and a door drops slightly, causing it to rub at the top of the latch side or the bottom of the hinge side. Tightening the screws often fixes it entirely. If a screw spins without gripping, the hole is worn; removing it, gluing a wooden matchstick or dowel into the hole and refitting gives it fresh material to bite into.

The rub location is diagnostic. Rubbing along the top edge suggests swelling or a dropped door. Rubbing at one specific point suggests a hinge or a frame that has moved. Rubbing at the bottom may be a floor covering rather than the door.

A candle or dry soap rubbed on the sticking edge reduces friction and is often enough to get through a humid spell.

If planing is genuinely needed, do it in the driest part of the year, remove the minimum, and seal the freshly exposed edge with paint or varnish. Unsealed edges absorb moisture faster, which is why doors sealed on the faces but not the top and bottom edges swell most.