Vejret i Chengdu (Sichuan) i december

Regulars are specific this city runs noticeably milder and less windy than Beijing at the same time of year, though it makes up for it with persistent fog and damp, grey days rather than the north's dry cold. Our row backs that cool, foggy read, 13.9C over 4.8C nights feeling 3C, with rain light at 10.4mm across 3.7 days but a real dampness that lingers, humidity at 73 percent, plus a trace of very rare snow, 0.1cm. Regulars are consistent the temperature itself seldom drops below freezing even in the depths of winter, so the discomfort here is more about persistent grey skies than genuine cold. A warm, water-resistant layer beats a heavy winter coat as the standard packing advice. The record: 6.3 hours of sun, an 11 kph wind and AQI 143.

Regulars call late April and May the season to come for, comfortable and not yet the peak-summer crowd, with one caveat repeated every time: it can rain at any point in the day regardless of the forecast. Our row backs the comfort at 28.1C reading as 29C over 17.8C nights, with 76.9mm across 10.7 days - real but not the region's wet-season extreme. Their timing warning for the pandas is worth carrying alongside the weather: early May specifically means avoiding the week around the 1st, a national holiday that crowds the panda centre regardless of how nice the weather turns out. The air is the real cost of this basin city, AQI 138, one of the highest columns recorded in this project. The record: humidity 66 percent, 8 hours of sun and a 12.7 kph wind.

Late November is pleasant in this valley and regulars say so while naming the catch themselves: the air can be poor and the sky hazy. Our row puts AQI at 148, the highest in this collection, with only 5.3 hours of sun a day to go with it. The month's argument is the animals. October and November, with early spring, are the two windows regulars name for the panda base, because the weather is mild for visitors and cold enough for the pandas, which stay active into the later part of the day rather than sleeping through it. Jiuzhaigou's autumn peaks in the first half of the month. Our row: 17.5C over 10C, 10.6mm of rain across 2.7 days, humidity 76 percent.

March brings the spring blossoms and regulars describe it as mild with little rain, quoting 15 to 26C against our row's 19.6C over 9.7C and 25.9mm across 7.1 days. Where our figures argue with the word sunny is the sunshine column: 6.7 hours a day is the low end of this dataset, because the Sichuan basin holds its haze - and our AQI 141 says the same thing. The good news is that the pandas agree with the grey. Regulars say mild-but-cool weather, and even rain, suits them and makes them more active, which is why early spring and late autumn are the two seasons they name for the breeding base. Go at opening, around eight in the morning, and book the timed online ticket in advance. The record: feels-like 18C days and 8C nights, humidity 70 percent.