Weather in Hangzhou in September

A good month. September is a solid month to be in Hangzhou. Highs average 29.2 °C, lows 20.2 °C, and rain falls on 12 days — nothing in the month is working against you.

September ranks 5 of 12 in Hangzhou: past the worst of the year but short of October, which is the month to book if the dates are open.

Rain on 12 days, 4 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 29.2 °C days and 20.2 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: 12 days top 30 °C — hot spells arrive, but they break. Across the twenty years measured, the hottest September day reached 39.9 °C and the coldest night fell to 10.1 °C, and the wettest single day dropped 76 mm — roughly 59% of the month's rain in one day.

September is moderately variable: 45 mm in the driest year against 305 mm in the wettest, around an average of 129 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind is light at 7.6 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 80%, high enough to notice on the warm days without dominating them.

How September sits in the year

The month is on the way down: 3.6 °C cooler than August, with October dropping another 4.7 °C. The first week and the last are not the same trip. Rain is the thing that moves: October brings 5 days less of it, so pushing the dates later buys drier weather.

Daylight in September

12.4 hours of daylight, losing 0.9 hours across the month. That is between Hangzhou's extremes of 14.1 and 10.2 hours, so days are long enough not to constrain the plan.

An inland climate

With no coast nearby, the year swings a fair way — 33.1 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage.

How busy it gets

Shoulder. The value months — prices ease off and you get the place closer to itself.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

September in Hangzhou versus nearby

If Hangzhou is one option among several, the nearby comparison is worth making. Shanghai is close enough to be a coin toss — within a degree on temperature, the same number of rain days. Nanjing is a better bet in September — within a degree on temperature, 3 days less rain.

So: September is a compromise. October is 21 points better and is what Hangzhou is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Hangzhou

See all twelve months in Hangzhou, or where else to go in September.