What to Wear in Paris in September

September is the month Paris dresses for itself. La rentrée puts the city back to work in the first week, and the street returns to a register that is quiet, worn-in and exact. Météo-France records a 21.5°C afternoon over a 13.0°C night, 44.7mm of rain across about eight days, and 174.7 hours of sunshine, close to six a day, which makes this the best-lit month of the Paris autumn. Nine degrees separate two in the afternoon from ten at night and you walk most of them. One unstructured layer solves that: carried at three, worn at eight, and never the trench.

The capsule

1. 
   01

   Navy slub-weave blazer, unstructured, patch pockets

   Carry it at three, wear it at eight. Nine degrees separate a 22°C / 72°F afternoon from a 13°C / 55°F night, and a gap that size is one layer rather than a coat. Two buttons, patch pockets, and a shoulder with no padding in it, so it reads as a jacket and not as office uniform; the slubby weave takes a fold in a bag and gives it back without a pressing. Navy rather than camel, because camel belongs to the trench and the trench belongs to October.

2. 
   02

   White cotton shirt, point collar, buttoned cuffs

   Wear this five days in seven and nobody counts. A fitted white cotton shirt takes the blazer at nine in the morning, goes under the camel crew at eight at night, and is the one piece that holds up in a patrimoine queue and at a late table without a change of clothes. Fitted rather than oversized, and with no chest pocket: a boxy shirt worn open reads as a beach in a month that went back to work.

3. 
   03

   Camel fine-gauge crew knit

   Thirteen degrees at ten at night is where this earns its place. A fine-gauge camel crew goes under the blazer when the terrace heaters are not on yet and sits alone over the shirt at lunch, and at this gauge it rolls into a bag instead of filling it. Camel rather than cream, because cream is what Paris October wears, and camel holds its own against the limestone the city is built from.

4. 
   04

   Dark indigo straight-leg jeans, cropped at the ankle

   Rigid indigo, straight through the leg, cropped a finger above the ankle, with no rips and no whiskering. Fifteen thousand steps across Haussmann pavement is an ordinary Paris day and denim at this weight takes it; the crop keeps the hem clear of a wet kerb on one of the eight rain days. Dark enough to carry a nine o'clock bistro table, which a light wash never manages.

5. 
   05

   Black pleated wide-leg trousers

   Swap these in at seven. Black pleated wide-leg trousers do the thing the jeans will not: hold a crease through an evening on the Fashion Week pavement in the 8th and a late table in the 2nd, and read finished with nothing over them but the shirt. Pleated at the waist and hemmed to brush the loafer, so the line runs unbroken and the 13°C / 55°F air stops at the ankle instead of running up the leg.

6. 
   06

   Black leather penny loafers

   Break them in at home, not on the rue de Rivoli. A black leather penny loafer on a flat leather sole is the September shoe, because the pavement is stone and the walking never stops; a new pair delivers blisters by the second museum. No logo and no trainer sole, which is the difference between reading local and reading visitor.

7. 
   07

   Navy pointed low-heel pumps

   The evening swap when the black trousers come out. A navy pointed pair keeps the line quiet at a late table and sits inside the blazer-and-scarf palette. Break these in before the trip too: the walk from the Metro is still stone pavement.

8. 
   08

   Black boxy leather bag, top handle, zip top

   The bag is where the compact umbrella lives, and across eight light rain days that is the whole of your rain planning. Boxy black leather with a zip top, a front flap pocket and side rings for a strap: hand-carried in a patrimoine queue, dropped onto the shoulder on a full Line 4 carriage. Big enough for the umbrella, a phone and a Navigo card, small enough that it never reads as luggage.

9. 
   09

   Navy-and-cream block-print silk square

   One square of silk does three jobs. Knotted at the throat it closes the gap the blazer leaves at 13°C / 55°F; folded around the bag handle it is the only pattern in the capsule; opened over the shoulders it covers you for a church on the patrimoine weekend. Navy and cream, so it sits inside the palette rather than fighting it, and small enough that it never turns into a shawl.

A suggested look — white cotton shirt, dark indigo straight jeans, black penny loafers, navy blazer, black top-handle bag.

What to avoid

• A trench as the hero coat — that is October here; at 22°C / 72°F you carry it all day
• Shorts — the city went back to work on 1 September, and the patrimoine rooms are not the place
• A full-size umbrella — 44.7mm across eight days; you will leave it on a café chair
• New shoes — 15,000 steps on Haussmann pavement finds every unworn seam
• Dressing for a photograph, not the Métro — the register is quiet, worn-in and exact