Weather: China, Mongolia, North Korea, South Korea, Taiwan, Tibet
Weather may be one reason why the philosophy of yin and yang developed in China. This ancient culture evolved in a climate rife with dualism. For starters, there's the monsoon. Less publicized than India's, this annual cycle of rain and drought is a fundamental part of life across the densely populated eastern half of the country. Although China faces the Pacific Ocean, it's actually the moisture from the further-away Indian Ocean that sweeps up from southeast Asia late each spring to kick off the monsoon. Places that barely see a drop of rain or a flake of snow in January are awash by August. Beijing gets almost a hundred times more precipitation in early summer than in early winter. Severe floods can strike China's colossal river valleys, especially the Yangtze, where more than three million people died from flooding and associated famine and illness in 1931 alone. By late September, the monsoon is being hounded southward by cool northerly winds that strengthen through the autumn and keep much of China dry and cold throughout the winter. Just as dramatic as the monsoon is the yearly oscillation in temperatures, especially in the eastern heart of China. No other populous part of the world gets this intense a combination of bitter winters and sweltering, humid summers. At least China's temperature cycle is more predictable than most.
Seasons tend to arrive close to schedule, and day-to-day temperature variations are subdued compared to those in North America. The pulses of cold air that cascade from Siberia onto the east China lowlands each winter can push into Southeast Asia and beyond. At 22°N, Hong Kong is one of the few coastal cities anywhere in the tropics that's experienced air close to the freezing mark. Despite all this chill, the intense aridity of Chinese winter means that the eastern cities avoid the persistent snowdrifts of Siberia, although what snow does fall in far northeast China can last for a long time. (Winter isn't as bad as it used to be across northern China – most recent winters have seen temperatures markedly above normal for long stretches.) If January and February are surprisingly cold for China's low latitude, the summers are just as hot and moist as you might expect. Perhaps the ideal time to visit eastern China is October, which can offer gorgeously sunny, crisp weather. To the west, China's more remote reaches offer a wholly different weather experience. The stark Gobi Desert, straddling the border of China and Mongolia, sits next to the Tarim Basin, former home of a giant glacial lake. Both the desert and basin get dry-roasted in the summer. Further north, the climate is more akin to Siberia's, with dry, bone-chilling winters and showery, coolish summers. The vast plateau of Tibet, sitting 5km/3 miles above its neighbours, is a meteorological world apart, much of it still unmapped.
Although all of this part of China is controlled by the annual monsoon, it's a large enough region to allow for plenty of differences. Winter is on the dry side everywhere, except for a few dustings of snow in the north and light rains once or twice a week further south, especially along the coast. Gusty Siberian cold waves that roll south every few days make some of their biggest inroads up the Chang Jiang (Yangtze) valley, chilling cities from Wuhan to Changsha. The Nan Ling Mountains keep the worst cold from reaching the southernmost provinces. Another relative mild spot is the Sichuan Basin, including Chengdu and Chongqing. In the spring, a few intense dust storms usually sweep from Mongolia across north and northeast China, stinging the eyes and obscuring visibility. Otherwise, the fast-warming weather – still on the dry side – is quite appealing. The leading edge of the summer monsoon rains typically hits south China by mid-May, then moves north in fits and starts. In June the rains often stall across the Chang Jiang Valley, forming a famous deluge-producing boundary known as the Mei-yu front that can linger for several weeks. The summer monsoon normally hits Beijing by late July and the far northeast plains in early August. This region's brief rainy season ends quickly as the monsoon retreats by late August. The mountains of the peninsula holding North Korea and South Korea, surrounded by water on both sides, are nearly as cold as northeast China in winter but more sultry in summer. To the west, the Sichuan Basin gets most of its monsoon rain at night, although its days tend to stay cloudy as well.
The rains often abate for a few weeks in late July and August across the core of east China, between the Chang Jiang Valley and the Nan Ling Mountains. It's then that heat and humidity build to insufferable levels. In such cities as Chongqing, Wuhan and Nanjing, nights may stay above 25°C/79°F, and many afternoons soar past 35°C/95°F, with no sea breeze to relieve the tropical torpor. Relief may come only with localized thunderstorms or with a typhoon moving inland. Typhoons are most likely to strike the southeast coast from July to September. The worst one in at least 50 years, Supertyphoon Saomai, killed more than 400 people in August 2006 when it stormed ashore south of Wenzhou packing winds of 150kph (150mph). Even though many recurve back toward the Pacific well before reaching China, about four or five typhoons make landfall in a typical year, and every few years one makes it as far as North Korea. They deserve respect, so be sure to heed warnings if you're near the coast (and watch for potential flooding along its track if you're further inland). Autumn sweeps quickly from north to south, with freshening breezes and rapidly cooling temperatures but plenty of sun. As the monsoon moisture retreats, it makes a last stand across southwest China, where multiday rains often fall across Sichuan, Yunnan and Guizhou provinces. The highlands of Yunnan, sitting above the tropical air masses of summer and the shallow cold blasts of winter, enjoy a “springtime all year” climate – exemplified in Kunming – that's considered one of China's most agreeable.
Positioned 200km/120 miles off the Chinese mainland, Taiwan gets a few spells of wintertime rain, as the monsoon flow rolls over the East China Sea and encounters the island's steep slopes. The northeasternmost town, Chilung, once suffered 55 consecutive days of winter rain. South of Tungshih, the winters are less prone to rain, but milder and more humid than in the coolish north. Summer is sweltering and wet across the whole island, opening with the Mei-yu downpours in May and concluding in August and September with sometimes-fierce typhoons that can produce torrents as they encounter the mountainous terrain. On 10–11 September 1963, Paishih received 1248mm/49.1in – one of the largest 24-hour rainfalls in Northern Hemisphere weather annals.
Northwest and Mongolia
Shielded from monsoon moisture by the Tibetan plateau and other highlands, this is one of Asia's driest pockets. The big divide is the Tien Shen range, which produces wildly varied weather across a small area. The basin's overall climate is on par with Beijing's, minus the summer rains – only about a day per month sees moisture. North of the Tien Shen, the Junggar basin gets nearly as warm as Beijing in summer but can drop below –30°C/–22°F in winter. Frequent light snows fall on foothill towns like Urumqi, with the heavier snowfall at elevation. The highest peaks maintain a snowpack through the summer. Oddly enough, China's summer hot spot is nearby, in a small basin sitting below sea level just southeast of the Tien Shen, where Turpan has reached 49°C/120°F.
Conditions in the Gobi of southern Mongolia can be brutal. Ulan Bator struggles to reach –18°C/0°F on a typical January day, and epic dust storms roar across the south each spring. However, Mongolia's highlands are just far enough east to benefit from monsoon-related showers, and the mid-summer sun helps make temperatures quite pleasant.
High-elevation weather usually affects only a sliver of land along a mountain range, but on the enormous Tibetan plateau it spreads from horizon to horizon. Many visitors wind up in the more temperate southern valleys, with summer readings much like you might find in central Scandinavia. Those venturing into the less-touristed reaches above 5000m/16,400ft may encounter July days that stay below 10°C/50°F and nights that plummet to freezing. The highest reaches may see more snow in summer than any other time of year (although that isn't saying much in such an arid regime). Monsoon showers and thunderstorms are heaviest toward the south, where the valleys are especially prone to nighttime rain. Spring and autumn in the valleys provide relative dryness and the most sunshine of the year, although it may snow on either edge of the moist season. While winter is predictably cold, it's not as bad as one might expect; the worst Siberian cold waves stick to the lower elevations of China.