Weather in Nanjing in September

A good month. September works. It is not the peak, but nothing about it fights you. Highs average 28.5 °C, lows 19 °C, and rain falls on 9 days — nothing in the month is working against you.

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

Rain on 9 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 28.5 °C days and 19 °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: 9 days top 30 °C — hot spells arrive, but they break. Across the twenty years measured, the hottest September day reached 36.1 °C and the coldest night fell to 10 °C, and the wettest single day dropped 69 mm — roughly 73% of the month's rain in one day.

September is moderately variable: 5 mm in the driest year against 255 mm in the wettest, around an average of 94 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind is light at 9 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 78%, high enough to notice on the warm days without dominating them.

How September sits in the year

The month is on the way down: 3.4 °C cooler than August, with October dropping another 4.9 °C. The first week and the last are not the same trip. Rain has already shifted: 6 days fewer than August had.

Daylight in September

12.4 hours of daylight, losing 1 hours across the month. That is between Nanjing's extremes of 14.2 and 10.1 hours, so days are long enough not to constrain the plan.

An inland climate

With no coast nearby, the year swings a fair way — 34.2 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage.

How busy it gets

Busy. Popular without being frantic; book the things you care about, improvise the rest.

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

September in Nanjing versus nearby

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

So: September works, with October the better month by 11 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Nanjing

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