Hong Kong (HK) weather in September

March here is cool by local standards - 15 to 25C is the range regulars quote and our row sits at 22.5C over 17.9C - with showers and sun in roughly equal measure. The thing they warn about is fog. Some March days it is thick enough that you cannot see across the street, and crucially it is worse with height and near the water than it is downtown, so the Peak and the harbour views are the part of the trip to keep flexible. Our 7.8 hours of sun inside 12 of daylight is that greyness counted. Humidity is already 81 percent. Layers rather than a coat; a long sleeve over a t-shirt is their formula. The record: 73.5mm of rain across 10.2 days and AQI 98.

Hong Kong-forum threads on typhoon season confirm August sits at the wettest, most humid stretch of the year, weather closely tracking July with steamy conditions and short, intense afternoon bursts rather than a long, steady soak. Posters run the actual odds for anyone worried: over decades of records, a serious storm signal has been called on average only a handful of days across the entire month, and even a direct hit rarely lasts longer than about half a day before easing. Regulars call the humidity, not any single storm, the real daily challenge - light, breathable clothing and frequent breaks in air-conditioned malls or the MTR are the standing advice regardless of the sky. The record: 31.2C days feeling like a punishing 38C, 26.7C nights, an extraordinarily high 339mm across 26.1 days, 88 percent humidity, a 28.8C sea and an unhealthy 75 AQI.

Hong Kong-forum threads on February split on one detail: the general climate is cool and dry, but when Chinese New Year lands in the month the weather is often described as cool and damp, closer to foggy than crisp. Crowds follow the lunar calendar more than the thermometer - the first day of the new year is called a 'very dead city' with museums and markets shut, while day three or four brings a crowded city as everyone comes back out. Outside CNY week, posters say to expect no crazy waits and zero typhoon risk this month. The record: 19.9C days, 14.9C nights, 34mm of rain across 6.2 days, 7.5 hours of sun. What the forums undersell: AQI runs 96 here, the second-haziest month on the calendar after December.

Hong Kong-forum threads on December packing are consistent: T-shirt weather by day, a light jacket or jumper for evenings and for indoor air conditioning that regulars warn runs full blast regardless of season, and one of the driest stretches of the year so an umbrella is a just-in-case rather than a must. The record matches: 20.5C days feeling like 19C, 15.3C nights, just 14mm total across under three days, and eight hours of sun. What the forum posts don't dwell on but the data does: December's AQI runs 112, the hazier end of the city's year, so it's a comfortable month to be outside but not always a clear one.