China is so large that there's no single best time to visit — it depends entirely on where you're going. The country spans tropical beaches in Hainan, permafrost in Manchuria, and a high-altitude desert plateau in Tibet. That said, spring (April–May) and autumn (September–October) are the best seasons for most of the country: mild temperatures, relatively low rainfall, and the summer crowds gone.
Spring (March–May)
A good time almost everywhere. Temperatures in Beijing and Xi'an reach a comfortable 15–25°C. Fruit trees blossom in Yunnan, cherry blossoms appear in eastern China, and the rice paddies around Guilin are at their greenest. Avoid the week around the Qingming Festival (early April) when Chinese travelers clog domestic transport.
Summer (June–August)
Peak season for tourists and the most difficult time to travel. It's hot and humid in most of eastern China, with temperatures in the Yangtze River cities (Wuhan, Nanjing, Chongqing) regularly hitting 38°C or more. Typhoons affect the southern coast from July to September. Tibet, Yunnan, and Inner Mongolia are better options in summer — cooler, greener, and less crowded than the big-city circuits.
Autumn (September–October)
The best season for most travelers. Temperatures drop to comfortable levels, the summer rains ease off, and the landscape — particularly in Hunan, Guilin, and northern China — is visually spectacular. The catch: the first week of October is National Day Golden Week, when hundreds of millions of Chinese travel simultaneously. Every train, plane, hotel, and tourist site becomes extremely crowded. Either avoid that week entirely or book everything months in advance.
Winter (November–February)
Cold in the north, mild in the south. Beijing can drop to -20°C at night in January; Harbin is colder still — which is precisely the point, as the January Ice and Snow Festival is spectacular. Southern destinations like Hainan, Guangzhou, and Hong Kong are pleasant in winter when the rest of the country freezes. Fewer tourists, cheaper prices.
Chinese New Year (late January or February, varying by year) brings the world's largest annual human migration. During the two-week Spring Festival period, transport is fully booked, prices spike, and many businesses close. Extraordinary if you want to see the celebrations; very difficult if you're trying to move around.
Tibet
The best months to visit are May, June, September, and October — the plateau is accessible and the skies are clear. July and August bring the monsoon; winter is bitterly cold and many guesthouses close.