Vejret i Hangzhou (West Lake) i september

Regulars are specific that visiting during the first week of this month can mean genuinely large crowds if it coincides with the Lunar New Year holidays, a real planning factor beyond the weather itself. Our row backs that cold, genuinely damp read, 12.6C over 3.4C nights feeling 0C, with 69.7mm of rain across 10.4 days and a trace of snow, 2.5cm, on top of a notably low sunshine average, just 5.6 hours a day. Regulars are consistent this counts among the less appealing months to visit overall, spring and autumn named as the genuinely lovely seasons here instead, with West Lake's willows and lotus flowers still months from their best. A warm, waterproof layer remains the standard packing advice regardless of the holiday timing. The record: humidity 76 percent, a 13.5 kph wind and AQI 108.

Regulars are careful to separate this cold from northern China's: it is a damp cold rather than a dry one, roughly zero to ten degrees, and the wind and moisture make it feel worse than the reading. Our row agrees exactly - 12.5C by day dropping to a felt 10C, and 3.4C nights that stand at 0C. Their advice is scarf and gloves for the extremities, and a covered seat if you take a boat out. They also make the case for coming: the bare trees around West Lake are worth the walk in December, and the crowds have gone. Rain is 47.3mm across 7.5 days, with 3.3cm in the snow column. The winter cost is the air, AQI 152, the highest of this city's year. The record: humidity 73 percent and 6.4 hours of sun.

Regulars here sort the year by crowds as much as weather, and their advice is precise: April before the first of May, and October after the national holiday week. May itself is the holiday, which means domestic crowds around the lake and peak prices for a few days at the start. The weather reason is in our row - 168mm across 13 days, the rain season that begins in April carrying on, with only 7.7 hours of sun a day. One poster's measure of it is that a small drizzle soaks you within ten minutes. Warmth has arrived, 28.7C reading as 31C at 76 percent humidity over 17.7C nights. Air is the other cost at AQI 122. The record: a 13.8 kph wind inside 13.7 hours of daylight.

Regulars recommend March for Hangzhou on two grounds: moderate weather and noticeably fewer large tour groups than the peak, with the early-spring blossom already out around West Lake. Their warning is that April is the rainy season, so come before it - which our row only half supports, because March itself already carries 106.6mm across 13.3 precipitation days under 6.2 hours of sun a day. Take the advice as comparative rather than absolute. What makes it bearable is the destination: several regulars describe a small boat on West Lake in light rain as the best version of it, the hills reduced to a Chinese ink painting and the crowds gone home. Our row gives 18.7C days over 7.9C nights, cool enough for a jacket. The record: humidity 75 percent and AQI 130.