Quick Answer: The turn week is defined by a large daily swing — often 10 to 12 degrees between morning and afternoon — rather than by cold. Dress for the coldest part of the day in removable layers, choose mid-weight fabrics that work in both halves (fine merino, cotton twill, ponte), and switch shoes and outerwear before you switch everything else, because those two carry the season more than the clothes underneath.

There is no announcement. One week the mornings are suddenly cold, the afternoons are still warm, and everything in your wardrobe is either too much or not enough.

Most people respond by keeping summer clothes going for another three weeks and being cold, or switching to autumn clothes and being uncomfortably warm by two in the afternoon.

The week is genuinely awkward. It is also short, predictable, and manageable with about four pieces.

What is actually happening this week?

A swing problem, not a cold problem.

The daily range widens sharply. Late summer and early autumn produce the largest daily temperature swings of the year — clear skies mean heat escapes overnight, so mornings are cold while afternoons still get full sun. Swings of 10 to 12 degrees are normal.

The sun angle drops. Lower sun means less direct warmth even at the same air temperature, which is why an October afternoon at 18C feels considerably cooler than a July one at 18C. Your clothing needs are not tracking the number on the forecast.

Buildings lag behind the weather by weeks. Offices, shops and public transport are still running summer cooling and will not switch for some time. Indoors is often the coldest environment of the day, which is completely counterintuitive and catches everyone.

And humidity falls. Drier air increases evaporative cooling from skin, so the same temperature feels cooler than it did a month ago at the same reading.

What should you actually wear?

Four items handle the whole week.

A fine knit as the base or mid layer. Merino or a lightweight lambswool at around 200gsm. Warm at 8am, not oppressive at 2pm, and it regulates in both directions in a way cotton does not.

A mid-weight trouser. Cotton twill, a light wool, or a ponte. Summer linen is too cool for the mornings and winter wool is too warm for the afternoons; the middle weight covers both ends.

One removable outer layer you can carry. A denim or cotton jacket, an overshirt, a light trench. It must fold or tie easily, because you will be carrying it for half the day. This is the piece that makes the whole week work.

Closed shoes. The fastest and most effective change of the season. A loafer, a trainer, an ankle boot. Bare feet in sandals on a 12C morning is the specific thing that makes people feel out of step with the weather.

Optional but useful: a large scarf. It handles the morning, the over-conditioned office, and the evening, and it takes no space at all in between.

What should you change first?

Shoes and outerwear, before anything else.

Shoes carry the season more than any other item. Swapping sandals for loafers or boots makes a summer dress read as autumn immediately, at no cost and with no other changes. This is the highest-leverage single move available in the transition.

Outerwear is second. A jacket over a summer outfit reads seasonally correct; the same outfit without one reads as leftover. These two changes let you wear your summer wardrobe several weeks longer, which is both economical and how most well-dressed people actually handle it.

Colour and fabric can wait. There is no need to abandon light colours in September — a cream trouser with a boot and a jacket is entirely correct, and the instinct to switch to autumn colours on a date rather than on a temperature is worth resisting.

What to actually put away: anything strappy, anything sheer, and any fabric that only works in real heat. Everything else can stay in rotation under layers, which is roughly two-thirds of a summer wardrobe.

The one thing to bring out early: the mid-weight knit, because the mornings arrive before the afternoons do.

Myth vs Fact: Transitional Dressing

Myth: you need a separate transitional wardrobe. Fact: you need about four mid-weight pieces that bridge the two. Buying a full wardrobe for six weeks of the year is how people end up with cupboards full of things worn twice.

Myth: layering means lots of thin layers. Fact: two well-chosen layers beat four thin ones, because four layers means four things to carry once it warms up. The number that works in practice is two, plus a scarf.

Myth: it is too warm for boots. Fact: an unlined leather ankle boot is comfortable well into the high teens and does more for a transitional outfit than any other item. Boots are not a winter-only category.

Myth: you should switch on the first cold morning. Fact: the first cold morning is followed by two warm weeks with reliable regularity. Change the shoes and the outer layer, keep everything else, and let the actual weather decide the rest.

Myth: cotton is the natural in-between fabric. Fact: cotton is comfortable but it does not regulate — it is cool when cool and warm when warm, with no adaptability. Fine merino is the genuinely transitional fibre because it insulates when cold and breathes when warm, which is exactly what a 12-degree swing requires.

FAQ: Transitional Weather Questions, Answered

How do I dress when the office is colder than outside?

Put the warm layer in the middle rather than on the outside — a knit you keep on all day, with a light jacket that comes off at the door. Leaving a cardigan permanently at your desk is the other reliable solution and costs nothing.

When should I actually pack away summer clothes?

Later than instinct suggests. Wait until you have gone two full weeks without wearing something, then store it. Most sleeveless tops and dresses stay useful under layers well into autumn, and only genuinely warm-weather-only items need to leave.

What is the one purchase worth making for this season?

A fine merino knit, in a colour that works with most of what you own. It covers cold mornings, over-conditioned buildings and cool evenings, works under a jacket and over a summer dress, and it is the piece most likely to be worn every week from now until spring.

TL;DR:

• The turn week is about a 10 to 12 degree daily swing, plus a lower sun angle, drier air, and buildings still running summer cooling.
• Four pieces cover it: a fine merino knit, a mid-weight trouser, one carryable outer layer, and closed shoes.
• Change shoes and outerwear first — they carry the season and let your summer wardrobe run several weeks longer.
• Two layers plus a scarf beats four thin layers, and merino beats cotton because it regulates in both directions.

The trap in this week is treating it as the start of autumn and dressing for a season that has not arrived yet. It is its own short season with its own rules, and it rewards adaptability over commitment. Get the four pieces working and this stops being the most annoying week in the wardrobe calendar — which, given it happens twice a year in both directions, is worth the small effort.