Formally, Shanghai’s climate is categorized as humid subtropical. Informally, you could de- scribe Shanghai’s weather as scorching hot and oppressively humid in the summer and surpris- ingly chilly in the winter, with about 6-8 weeks of absolutely marvelous weather in the spring and the fall.
During the hottest months of the year, July and August, you will find yourself moving from one air conditioned environment to another, most likely with haste, as many describe the effect of the humidity as similar to donning a steaming hot blanket. Central government mandates on power usage in public buildings restrict air con- ditioning usage to no lower than 26°C (78°F) in the summer, so outside of your private spaces there is often little escape on days when the humidity is at its highest. Occasionally a bout of rain will offer some temporary respite, but never for long. For weeks on end, it will seem as if the daytime temperature is stuck at 32°C (90°) which feels more like 40°C (104°F) due to the humidity. Annually, Shanghai has about 10 days that reach 35°C (95°F) which, when you factor in the humidity, is (insert your own expletive here) hot.
It shouldn’t be surprising that when school breaks up for summer vacation in late June, there is a mass exodus of expats from the city, like wildlife fleeing a forest fire, leaving many popular foreign compounds looking like ghost towns. Only when summer’s grip lessens and the new school year looms do the foreign deni- zens begin to return to their habitat.
During the coldest months of the year, January and February, Shanghai gets surprisingly chilly. It’s not the temperature so much (it rarely gets below freezing) as it is the humidity amplifying the effect of the cold, which seems to go right through your clothes.
The government has a policy that restricts temperatures in buildings to no more than 20°C (68°F) during the winter months in order to conserve energy. It is not uncommon to see locals wearing winter jackets indoors during the winter months in an effort to save energy and money.
Adding to the winter woes is the fact that most apartments in Shanghai don’t have central heating or double pane windows to keep the chill out. This is changing, however, as central heat and even heated floors are becoming more popular, particularly on the higher end of the property scale. So if you are doing your look-see trip to Shanghai during the warmer months, take note of these amenities as you will surely thank yourself come winter.
In stark contrast to the rest of the year, the months of April, May, October and November are truly glorious, with temperatures hovering around 20-22°C (68-72°F) ample sunlight and low humidity (particularly in the fall).
While this section may sound like more of a warning than a description, rest assured that you will acclimate eventually. For the truly bold, spending a summer in the city with the air con- ditioning turned off would certainly hasten the process. It also explains why locals don’t seem much bothered by the weather at all.