The month of May is a transition month in China; a bridge from winter to summer. The Siberian High is beginning to recede and becoming warmer in the rapidly growing sunshine of Siberia's northern latitudes. As this high pressure system pulls north, northern China sees its first relief from the bitter cold of winter since September or October. The primary storm track is still in Siberia (near 60°N) although the cold fronts it drags behind begin to extend further and further south. The Pacific High is growing in influence and the Indonesian Low is developing over the warming waters of the western Pacific.
With the approach of spring, moisture laden southwesterly winds begin sweeping northward into China ushering in the monsoon season. As spring advances northward across China, it heralds a beautiful time of year when daytime temperatures climb to between 20 and 30°C (68 to 86°F) and there is less rain. Sub-freezing temperatures are still possible across northern China, but by the end of the month frosts and freezes less common on the Manchurian Plain and across the northern plateaus. Daytime temperatures range from 20 to 30°C (68 to 86°F). Although it can become quite hot during the day, nights can still get bitterly cold and bring frost.
Springtime on the North China Plain is spectacular, a time when the entire landscape seems to explode in shades of green. . Clear sky can be expected. It is temperate and cool. The trees on Beijing's Fragrant Hill (Western Hill) are covered with new growth. Temperatures begin to climb in this region during May. The month still can expect bouts of cool, dry weather and frequent strong winds that blow dust across the plain, but warm and humid winds from the south intrude to bring very pleasant weather. There is no real dividing line between winter and spring in Beijing and, spectacular as it is, it does not last long. Before you realize it, spring is gone.
In southern and southeastern China, day temperatures ranging between 20 and 25°C (68 to 75°F). However, it can be miserably wet and cold, with perpetual rain or drizzle. On Taiwan, the brief transition months of April and May bring generally clear conditions and cool, moderate temperatures.