On the island of Hainan, the southernmost province of China, the climate is almost tropical, with very mild winters, and long and hot, muggy and rainy summers. In fact, the average January temperature is near 20 °C (68 °F) in the north, and slightly higher in the south. The rains are abundant from May to November on the eastern side, while the western side is more sheltered, and receives moderate rains only from June to October, and even abundant in August and September; therefore, total annual rainfall hardly reaches 1,000 mm (40 in), not a lot for a tropical area, while on the eastern side of the island it rains about twice as much.

On the northern coast, where the capital, Haikou, is located, the average January temperature is 18 °C (64 °F). In winter, the north-east monsoon brings cloudy days when there are some drizzles, or fog can form. Sometimes cold and windy days can occur, with highs around 15 °C (59 °F) or even below. In January 1977, the temperature dropped to 3 °C (37.5 °F), while in January 2016 it dropped to 6 °C (43 °F). Here are the average temperatures.

In Haikou, rainfall amounts to 1,600 millimeters (63 inches) per year and is abundant from May to October.

In Haikou, the sun shines about 2,000 hours per year: in winter the sky is often cloudy, while from May to September it shines a little more often than in the southern Chinese mainland.

The sea temperature is similar to that of Guangdong, although it is a bit warmer in winter. However, it is a bit cool for swimming from January to March, while it is pleasantly warm from May to October.



On the southern coast, where the tourist resorts are found, the winter temperatures become milder, and the climate can be defined as tropical, in fact the January average is 22 °C (72 °F). However, from November to March sometimes the night temperature can drop to around 10 °C (50 °F). Here are the average temperatures of Sanya, the largest city of the southern coast.

Here the rains amount to 1,400 mm (55 in) a year; the trend is very similar to that of the north coast, but the period November-April is drier because this coast is sheltered from the north winds.

In winter, on the southern coast the sun shines more often than on the northern one.

On the southern coast, the sea too is warmer in winter, in fact the water temperature does not drop below 23 °C (73 °F) in January and February: after all, you can swim even in winter.

On this island, the interior is occupied by hills and mountains, where lush forests grow. The highest mountain is Wuzhishan (the "five finger mountain"), 1,840 meters (6,040 feet) high. On the top, the daytime temperature is around 10 °C (50 °F) from December to February, and around 20 °C (68 °F) from May to September. However, access has recently been closed to foreign tourists.

Typhoons

Together with Southern China, Hainan can be hit by typhoons, tropical cyclones of Southeast Asia. Typically, typhoons occur in this area from June to mid-November, but sometimes (though very rarely) they have affected this area outside of this period, in April or in May.

Best Time

If you want to go on excursions, you can choose the coolest period, from mid-November to late March.
For a beach holiday, you can choose the month of April (or even May, which, however, is warmer and rainier). The May-September period is hot and muggy, with showers and thunderstorms even strong, but also with some hours of sunshine. From June to mid-November, typhoons can occur, which bring strong winds and torrential rains.
On the southern coast (see Sanya), there can be days warm enough for sunbathing and swimming even in winter. On cool and cloudy days, you can go on excursions on the island.