In the island of Taiwan, formerly Formosa, the climate is tropical, with hot and rainy summers, and mild winters. The period May-September is very rainy throughout the country, due to the summer monsoon, while in the other seasons, rainfall depends on latitude and slope exposure. However, winter is the least rainy season everywhere.
In winter, the temperature is pleasant in the south, where highs are about 23 °C (73 °F) in January, and the sun often shines, while in the north (see Taipei) the climate is cooler and cloudier, with an average maximum temperature about 18 °C (64 °F). Due to both maritime influence and low latitude, night-time temperatures are rarely cold and never drop below freezing (0 °C or 32 °F). However, sometimes in the north there can be very cool days, with highs about 10/12 °C (50/54 °F).
In spring, in April and early May, early thunderstorms begin to occur in the afternoon, starting from the north and the interior. The monsoon arrives in the island around May 10 - May 20, coming from the south. It brings heavy rains throughout the island, but especially along the southwest coast, from Tainan to Hengchun, as well as in the highlands of the interior.
Summer is hot, humid and rainy, with more frequent rains (unlike in winter) along the southern coast. Temperatures are uniform from north to south: in July and August, the daily average in the plains hovers around 29/30 °C (84/86 °F). The north-west coast, from Taichung to Taoyuan, experiences a relative decrease in rainfall in July. The amount of sunshine in summer is acceptable, because the tropical rains are usually intense but short-lived, however, in this season there's a sticky and unpleasant heat.
During summer, the island is often affected by typhoons, the tropical cyclones of South-East Asia, able to bring strong winds and torrential rains; they typically cause heavier damage along the east coast.
After the monsoon, in autumn, from October to December, the rains decrease and the muggy heat is replaced by a more pleasant weather. The only area which remains fairly rainy is the east coast, where more than 100 millimetres (4 inches) of rain per month fall still in autumn (see Hualien).

The capital Taipei is located in the northern part of the island, which is the rainiest along with the north-east, and in winter is the coolest. The average temperature goes from 16 °C (61 °F) in January, to 30 °C (86 °F) in July. In summer, the "urban heat island effect", generated in the big city, makes the heat even more unpleasant, but fortunately the buildings are equipped with air-conditioning.
Here are the average temperatures of Taipei.
Average temperatures - Taipei

Taipei	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Taipei	J	F	M	A	M	J	J	A	S	O	N	D
Min (°C)	14	14	16	20	23	25	27	26	25	23	20	16
Max (°C)	18	19	21	25	28	31	33	33	30	27	24	20
Min (°F)	57	57	61	68	73	77	81	79	77	73	68	61
Max (°F)	64	66	70	77	82	88	91	91	86	81	75	68

Here 2,400 mm (95 in) of rain per year fall, with a peak in the hottest period, from June to September. Here is the average precipitation.
Average precipitation - Taipei

Taipei	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Taipei	J	F	M	A	M	J	J	A	S	O	N	D	Y
Prec. (mm)	85	170	180	180	234	325	245	320	360	150	85	75	2405
Prec.(in)	3.3	6.7	7.1	7.1	9.2	12.8	9.6	12.6	14.2	5.9	3.3	3	94.7
Days	14	15	16	15	15	16	12	14	14	12	12	12	166

However, there is no dry season, and in winter the sky is often cloudy, because the winter monsoon, which is originally dry as it comes from the Asian mainland, picks up moisture over the sea and brings clouds, mists and some rain in the northern part of the island. Even in spring the sun can be seen rarely. Overall Taipei is a dull city: in a year there are only 1,400 hours of sunshine. Here are the average sunshine hours.
Sunshine - Taipei

Taipei	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Taipei	J	F	M	A	M	J	J	A	S	O	N	D
Sun (hours)	3	3	3	3	4	4	6	6	5	4	3	3

Along the northern coast, the sea is warm enough for swimming from May to October, while in winter it becomes very cool, as we can see from the sea temperature at Keelung, about 20 kilometres (12 miles) northeast of Taipei.
Sea temperature - Keelung

Keelung	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Keelung	J	F	M	A	M	J	J	A	S	O	N	D
Sea (°C)	18	18	19	22	25	27	28	28	27	25	22	20
Sea (°F)	64	64	66	72	77	81	82	82	81	77	72	68

As mentioned, in the south the winter warmer, as we can see from the average temperatures of Tainan.
Average temperatures - Tainan

Tainan	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Tainan	J	F	M	A	M	J	J	A	S	O	N	D
Min (°C)	14	15	18	21	24	26	26	26	25	23	20	16
Max (°C)	23	24	26	29	31	32	33	32	32	31	28	24
Min (°F)	57	59	64	70	75	79	79	79	77	73	68	61
Max (°F)	73	75	79	84	88	90	91	90	90	88	82	75

In Tainan, on the south-west coast, 1,700 mm (67 in) of rain per year fall, and the dry season is long, from October to March, while showers begin to increase in April. Here is the average rainfall.
Average precipitation - Tainan

Tainan	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Tainan	J	F	M	A	M	J	J	A	S	O	N	D	Y
Prec. (mm)	15	30	40	80	175	370	360	395	180	30	15	15	1700
Prec.(in)	0.6	1.2	1.6	3.1	6.9	14.6	14.2	15.6	7.1	1.2	0.6	0.6	66.9
Days	4	5	5	7	9	13	12	15	10	2	2	3	87

In Tainan, and in general in the south, the winter, in addition to being drier, is also more sunny than in Taipei. In Tainan there are 2,200 hours of sunshine per year.
Sunshine - Tainan

Tainan	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Tainan	J	F	M	A	M	J	J	A	S	O	N	D
Sun (hours)	6	6	6	6	6	6	7	6	6	6	6	6

The sea is warm enough for swimming all year round along the south coast. In winter, however, the air temperature, though mild, is a bit low for beach life also in the south. Here is the sea temperature in Tainan.
Sea temperature - Tainan

Tainan	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Tainan	J	F	M	A	M	J	J	A	S	O	N	D
Sea (°C)	23	23	24	26	27	28	29	29	28	27	26	24
Sea (°F)	73	73	75	79	81	82	84	84	82	81	79	75

The interior of the island is occupied by mountains, which reach their highest point in Yushan, 3,952 metres (12,966 feet) high, whose name means "Jade Mountain", due to the contrast created in winter between the snow-capped peak and the sky in the background. Above 2,000 metres (6,500 feet), winter is quite cold, and there's some chance of snow and frosts, while summer is cool but very rainy. On the top of Yushan, in the winter months the average temperature is around freezing, while in summer it's around 8 °C (46.5 °F). On average, even 3,000 mm (118 in) of rain or snow per year fall, with a remarkable maximum in summer, while snow is frequent in winter. Here are the average temperatures.
Average temperatures - Yushan

Yushan	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Yushan	J	F	M	A	M	J	J	A	S	O	N	D
Min (°C)	-5	-4	-2	0	3	4	4	4	4	2	0	-3
Max (°C)	3	3	5	8	10	12	13	13	13	13	10	6
Min (°F)	23	25	28	32	37	39	39	39	39	36	32	27
Max (°F)	37	37	41	46	50	54	55	55	55	55	50	43

The Penghu Islands (called Pescadores in the Portuguese era), located in the Taiwan Strait, are less rainy than the main island, since they receive about 1,000 mm (40 in) of rain per year.

On the north coast, near Taipei, the sea temperature drops to 18 °C (64 °F) in January and February, and to 20 °C (68 °F) in the Pengchu islands.


As mentioned earlier, Taiwan can be hit by typhoons, tropical cyclones of Southeast Asia; actually, Taiwan is one of the most affected countries, also because the mountains that cross the island create the conditions for torrential rains: it is not by chance that in some places, during the most intense typhoons, a total of more than 1,000 mm (40 in) of rain have fallen in a few days. Typically, typhoons occur in this area from June through October, although they are more frequent from mid-July to early October. However, recently, perhaps due to global warming, sometimes they have passed outside of this period, though without reaching high intensities, as happened in late April 2003 with Typhoon Kujira, in May 2006 with Typhoon Chanchu, or at the beginning of December 2004 with Typhoon Nanmadol.


The best time to visit Taiwan runs from November to March, being the mildest, and outside the monsoon rains, as well as the typhoon season. The east coast, however, is very rainy still in November.


In winter: spring/autumn clothes, sweatshirt or sweater, light jacket, raincoat or umbrella. For the high mountains, down jacket, rain jacket, hat, gloves, scarf.
In summer: tropics-friendly, loose fitting clothing, a light sweatshirt and pashmina for air-conditioned places, light raincoat or umbrella.
For the reef, equipment for snorkeling, water shoes or rubber soled shoes.
For the high mountains, warm jacket, rain jacket, hiking boots.