A flaking scalp is not necessarily a dry one, and the difference decides everything you do next.
Flaking is a symptom, not a diagnosis. It turns up on scalps that have genuinely run short of moisture, and on scalps producing plenty of oil, and those two situations respond to almost opposite handling. Working out which one you have is most of the job.
Dry scalp: skin that has run out of water
A dry scalp is the same story as dry skin anywhere else on the body. The outer layer of skin — the stratum corneum — holds water in place using a mix of lipids and natural moisturising factors. Deplete those, and water leaves faster than it is replaced. The surface stiffens, and it sheds in small, fine, pale flakes.
The tells are texture and feel. The flakes are dry and powdery, and they fall away on their own — they end up on your shoulders rather than lodged in your hair. The scalp itself feels tight, particularly in the 20 minutes after a hot shower. And it rarely happens in isolation. If your scalp is genuinely dry, your shins, forearms, and the backs of your hands usually are too.
The oily kind of flaking, which is more common than men expect
The other version looks like flaking and behaves like something else entirely. The flakes are larger, softer, and faintly greasy. They cling to the hair near the root and to the scalp itself, and shifting them takes a fingernail rather than a shake of the head. The scalp underneath is often oily, sometimes pink, and itchy again within a day or two of washing.
The mechanism is worth knowing. Malassezia is a yeast that lives on almost everyone's scalp as a normal resident. It feeds on sebum, breaking those oils down into by-products that some people's skin reacts to. The skin responds by turning its cells over faster than usual, and cells that would ordinarily be shed invisibly come away in visible clumps instead. That process sits behind common dandruff, and behind seborrhoeic dermatitis at the more persistent end.
Distribution gives it away. Because it follows sebum, it tends to show up where the sebaceous glands are densest: the scalp, the eyebrows, the creases beside the nose, and behind the ears. Ordinary dryness does not single out those places.
Why September makes both of them worse
Autumn is the point in the year when the two causes converge. Outdoor air holds less water, indoor heating comes back on and dries it further, and showers get longer and hotter. For a dry scalp, that combination draws moisture out and strips the lipids that hold on to what remains. Sebum production, meanwhile, does not take the season off — so the oily version carries on as before, just under a hat.
Handling them differently
The instinct in both cases is to wash less often. For a dry scalp that is usually right. Hot water and aggressive surfactants tend to be the aggravating factor, and moving to cooler water and a gentler wash removes the cause rather than covering it. Let the water run tepid, and rinse the roots properly — residue left sitting on the scalp is an irritant in its own right.
For the oily kind, washing less is precisely wrong. Sebum is the substrate for the whole process, and leaving it to accumulate between washes gives it more to work with. Wash more regularly, not more aggressively. Use your fingertips rather than your nails; scratching a flaking scalp breaks the surface and makes the itch worse instead of settling it.
One habit helps whichever version you have: stop going after the flakes directly. Picking at them, scrubbing, and towel-drying as though you are sanding a floor all provoke more shedding than they remove.
Where grooming ends
There is a point at which this stops being a grooming question. Thick silvery scale, well-defined red patches, skin that weeps or bleeds, flaking that spreads onto the face or chest, or flaking alongside hair coming out — none of those are problems to work through with a different shampoo.
If the flaking is persistent, painful, spreading, or getting worse despite sensible washing, see a GP or a dermatologist.