Paris weather in September

Paris in September, as the forum puts it, starts hot and finishes temperate — most days in the low-to-mid 20s°C, with the occasional push toward 28 and the occasional cool spell in the high teens. Regulars rate it some of the year's best weather but still insist on layers and a windproof outer, because a fortnight here can hand you sun, chill and rain in turn. The catch is crowds rather than climate: fashion week and convention season make September busy, and October is the quieter month.

The recurring July question on this board is not what to pack but whether the room has air conditioning, and the regulars' answer is that if you have it at home you will want it here. Their range is wider than any average: the high twenties are common, the low thirties not unusual, and the high thirties happen. Our row's 26.9C is the middle of that, over 15.1C nights, at 65 percent humidity with 50.2mm of rain across 8.5 days. The other half of their warning is that the city's cooling is thin - many buildings have none, and the places that do often only take the edge off. Daylight runs to 15.7 hours with 11.4 of sun. The record: a dew point of 12.7C, a 16.3 kph wind and AQI 43.

Paris-forum threads asking how wet and miserable December really is land on a fair-but-not-dire verdict: one of the rainier, greyer months of the year, short days with real daylight running only from around 9am to 4:30pm, but posters are consistent it's rarely bitterly cold, generally staying above freezing with actual snow settling on the ground a genuine rarity. Regulars describe the month as swinging between drizzly, damp stretches and surprisingly bright, clear days within the same week. The Christmas illuminations along the grand boulevards, the markets and lit-up department store windows are repeatedly called the real payoff despite the shorter days. A proper waterproof coat, scarf and gloves beat a fashion-first umbrella, since wind off the Seine can turn one inside out fast. The record: 9.6C days feeling like 6C, 3.5C nights, 74mm across 12.8 days, 0.7cm of rare snowfall, 89 percent humidity and just 3.2 hours of sun.

Paris-forum threads on August describe a city running on a different rhythm: many Parisians take their own two-to-three-week vacation this month, so neighborhoods outside the tourist core feel noticeably quiet while the Louvre-and-Eiffel-Tower circuit stays as busy as ever. The back half of the month, from August 15 onward, is called the quietest stretch of all. Posters are also blunt about the heat: it can be hard to bear, and air conditioning is far from guaranteed in hotel rooms, with no sea or mountain breeze to cool the city down. The upside: hotel rates often drop with the extra vacancies, and with 45,000 restaurants across the city, finding one open is never actually hard despite the closures. The record: 26.8C days feeling like 27C, 14.8C nights, 51mm of rain across 8.6 days and 10.5 hours of sun.

Paris-forum threads on June crowding land in the middle: busy at the marquee sites, but posters say the city is spread out enough to rarely feel crowded away from them, and early June still reads as shoulder season before the July-August peak. More than one thread flags June as one of the pricier stretches to book a room, on par with summer proper despite the lighter crowds. The advice is to front-load the trip - early June is warm without being muggy, and posters note the back half of the month turns noticeably stickier. The record: 25.2C days, 13.6C nights, 71mm of rain across nearly twelve days, 11.3 hours of sun and over sixteen hours of daylight.