Weather in Shanghai

August is the warmest month (average 28.8°C, high 31.9°C) and January is the coolest (average 4.8°C, low 1.1°C). That 24.0°C swing in monthly averages is the first thing to plan around in Shanghai.

Rain is wet season runs from April to September, inside an annual total of 1286 mm. The wettest month is June at 195 mm; the driest is December at 53 mm. Shanghai is in China at 31.2°N. The 2001–2020 NASA POWER daily record describes a humid subtropical climate. On this site the months that score closest to a 22°C day, lighter rain, and moderate humidity are May, September, and October.

Rain through the year

The wet season in Shanghai starts in April and ends in September (April, May, June, July, August, and September). June is the core of it at 195 mm. December is the other extreme, with 53 mm.

Humidity peaks near 82%. That usually lines up with the wetter months rather than the hottest ones.

How warm Shanghai gets

The heat peaks in August, when the typical afternoon is 31.9°C. The opposite pole is January, when mornings average 1.1°C.

Across the year the mean afternoon high is 21.0°C. If you want the smallest day–night shock, look at months where the high and low sit close together; August nights still hold 25.7°C.

Distinctive months in Shanghai

The year bottoms out in January. Plan for 1.1°C at night and 8.4°C in the afternoon. February stands apart from the months beside it: 10.4°C / 2.4°C and 78 mm. March brings 88 mm and 11 rainy days; temperatures run from 5.6°C to 14.7°C. April is when the wet season typically starts in Shanghai: highs near 20.3°C, and rainfall jumps to 95 mm (11 rainy days). May: 25.4°C high, 16.5°C low, 105 mm rain, 77% humidity. June is the wettest month — 195 mm and 16 rainy days, with 81% humidity.

July brings 148 mm and 16 rainy days; temperatures run from 25.5°C to 32.0°C. August is the warmest month. Afternoon highs average 31.9°C and nights settle near 25.7°C, with 173 mm of rain. By September the wet season is ending. Shanghai still sees about 136 mm, but the next month is usually leaner. October brings 77 mm and 7 rainy days; temperatures run from 15.9°C to 23.4°C. November stands apart from the months beside it: 17.7°C / 10.0°C and 71 mm. December is the driest month, averaging only 53 mm across 8 rainy days. Highs sit near 10.8°C.

When the score favours a visit

The three months with the highest comfort score are May, September, and October: May (20.9°C average, 105 mm, 77% humidity); September (24.9°C average, 136 mm, 78% humidity); October (19.7°C average, 77 mm, 76% humidity). They fall in calendar order. The score rewards averages near 22°C, lower rainfall, and humidity near 60%. It is a climate score, not a festival or price calendar.

If you want the wet season itself — fewer crowds, greener landscape, heavier rain — aim at April–September instead of the score.

Shanghai and other cities in China

Hangzhou is about 161 km away: Shanghai is about as warm as Hangzhou at the hot peak and 141 mm drier over the year than Hangzhou. Hangzhou’s wettest month is June (230 mm) versus June here.

Nanjing is about 270 km away: Shanghai is 0.4°C warmer than Nanjing in its hottest month and 89 mm wetter over the year than Nanjing. Nanjing’s wettest month is July (243 mm) versus June here.

Hefei is about 402 km away: Shanghai is about as warm as Hefei at the hot peak and 132 mm wetter over the year than Hefei. Hefei’s wettest month is July (227 mm) versus June here.