Shanghai weather is generally mild and moist, with four distinct seasons - a pleasant warm spring, a hot rainy summer, a comfortable cool autumn and an overcast cold winter. The region's location at the estuary of the Yangtze River to the East China Sea makes it so wet that it rains for about one third of the year.
Introduction to Shanghai Climate
With a subtropical maritime monsoon climate, Shanghai is generally mild and moist. Although situated in the southern part of China, it still has four distinct seasons - the warm spring and the cool autumn are comfortable for travel, while the hot rainy summer and the overcast cold winter are far less pleasant.
Spring in Shanghai is from March to May. This is the best season in a year for traveling. Spring flowers in bloom make the city lively and attractive. The temperature is comfortable around 20 C (68 F). Light rain happens however will not disturb your trip. Long-sleeved shirts, thin sweaters or coats are suitable for this time.
Summer here is long from June to September. With high temperature and abundant rainfall, the city can be very sweltering at this time. The highest temperature occurs in July or August. For 10 days or so in these two months, the temperature can be above 35 C (95 F). You had better avoid the hottest time around 14:00. Wear cool clothes such as T-shirts and shorts and drink more water to prevent heatstroke and dehydration.
There is a 'Plum Rain Season' (Meiyu Season) from mid-June to early July. This lasts for nearly one month commencing in early summer when the plums ripen along the middle and lower reaches of the Yangtze River. During this period, the rainfall often equals 25% of the city's annual total! Showers alternate with sunshine and the weather is really hard to predict. The frequent rain may spoil your travel plan. From late August to mid-September, typhoons can bring heavy rain in their wake. These two periods are best avoided by travelers but should you decide to visit be sure to bring an umbrella. Of course, the umbrella can also be used as a protection from the strong ultraviolet radiation on the sunny summer days.
Autumn of the region comes in October and November. The temperate weather makes this season good for travel. It rains often in autumn except in the late November. Long-sleeved shirts, sweater and coat are appropriate.
Winter in this area is from December to the next February. The coldest period is from the end of January to early February - usually during the Chinese Spring Festival. The worst of the cold usually lasts for only a few days and it seldom snows. The temperature is not as low as some cities in north China like Beijing, but the humid cold wind is a torture for even the northerners. A sweater and overcoat are necessary in winter.
* Shanghai's urban sprawl greatly affects the climate. The urban area is usually hotter and drier than the suburbs and this effect aggravates the rainfall and pollution, calling for people's attention to protect and improve the environment.