Except for the windy, chilly winter months, Shanghai teems with tourists and business travelers, most notably May through October. July and August are unpleasantly hot and humid as a rule; locals often sleep on cots on the sidewalks to escape the pent-up heat of the day in their small apartments. Shanghai's busiest tourist periods coincide with its mildest weather in the spring and fall. September and October are really the ideal times to visit, but they're also popular times for meetings and conventions, leading to high hotel occupancy and uncompetitive room rates. To avoid the big crowds and still enjoy decent weather, the best time to visit is in late March or late October/early November. Besides the climate, the other major consideration in the timing of your visit should be the domestic Chinese travel season.
Shanghai, located on the 31st parallel north, has a climate comparable to that of the southeastern coast of the United States, except that Shanghai's summer is hotter. Spring, from mid-March to mid-May, is mild but rainy. Summer, from mid-May to mid-September, is oppressively hot and humid. Winter, from mid-November to mid-March, is damp and chilly, but there is seldom snow and the daytime temperatures are usually above freezing. Autumn, from mid-September to mid-November, is the most comfortable season, being neither too hot nor too rainy, but typhoon-propelled rains can strike in September.
National holidays observed in Shanghai with days off include New Year's Day (Jan 1), Spring Festival/Chinese New Year (first day of the lunar calendar: Feb 3, 2011, Jan 23, 2012), Qingming Festival (usually Apr 5 on the Gregorian calendar; Apr 4 during leap years), Labor Day (May 1), Dragon Boat Festival (early June on the lunar calendar), Mid-Autumn Festival (Sept on the lunar calendar), and National Day (Oct 1).
Spring Festival, the Chinese New Year, is the most important holiday. Officially, it is a 3-day national holiday (usually expanded to 7 days, making the weekend after the 7-day holiday normal working days). On the first 3 days, banks, offices, and many workplaces are closed. In reality, the effects of this holiday are felt from 2 weeks before the date until 2 weeks after, as Chinese travel to and from their hometowns, which may be very far from their place of work. The 15th day of the New Year is marked by the Lantern Festival celebrations.
The National Day (Oct 1) holidays will also last 7 days. While offices, banks, smaller restaurants, and some sights may be closed for part of each holiday period, you will find in Shanghai that hotels that normally cater to business travelers will offer significant discounts during those times.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.