Taiwan has a subtropical climate with two basic seasons. The island is greatly affected by the seasonal exchange of warm ocean currents and air masses between the ocean and Mainland China. Taiwan lies in the path of severe tropical cyclones known in East Asia as typhoons. With their violent winds and extremely heavy rainfall, these storms often cause severe damage, especially to crops. The monsoons in the winter (from the northeast) and summer (from the southwest) are the main factors controlling the climate of Taiwan.

      Even though it is a small island, the climate also varies considerably depending on what area you are in (lowlands or mountains) and what time of year it is (winter, summer). There are basically three climatic regions: the north & east coastal region, the southwest coastal region, and the mountains.

      The brief autumn (October and November) has the most delightful weather island-wide, though typhoons are possible in October. Autumn temperatures are mild and dry, especially in the southwest. Throughout Taiwan, the driest months occur between November and February.

     Winters are short and usually mild while summers are generally long and accompanied by high humidity. The summer is statistically the wettest season on the island, although it comes in unexpected bursts from thunderstorms that seem to appear and disappear without warning. It is clear and sunny most of the time but a sudden thunderstorm may appear and drop an enormous amount of water in a short time as well as cause enormous damage to crops, property and flood cities up to the 1st story of a building as was the case in certain areas of Taipei in the past. The mean monthly temperature in the lowlands is about 16 deg C in the winter, and ranges between 24C-30C the rest of the year. The relative humidity averages about 80%.

      Winter in the north & east coastal region, which include Taipei, brings the northeast monsoon, which lasts about six months from October to late March. During this time the north/east is the wettest part of the island, with heavy cloud cover and frequent showers. It can be cool, and occasionally chilly, but frost is rare in the lowlands, where most of the population lives and works. The temperature can plummet 10C or more in just a few hours during this time. You might be comfortable in shorts and a tank top in the morning and then by noon you’ll have to put on warmer clothes. The central and southern parts of the island, however, have sunnier winters, with pleasantly cool, dry days, with less than 30% of their annual precipitation falling at this time. In fact, while a downpour is occurring in the city of Taipei, it can be completely dry and clear in the central and southern areas of Taiwan (ie. Taichung and Kaohsiung).

      May and June begins the annual "Plum rain" season, which brings a lot of precipitation. During the summer in the north/east region the skies may be clear but the rains come in short, unexpected bursts of heavy downpours, mostly in the afternoon, and it can be extremely sticky, hot, and very uncomfortable for people used to cooler/dry climates. Rainfall is most abundant in the north with 60% of precipitation falling between May and October.

      Summer in the southwest region is also extremely hot and humid, with frequent afternoon showers because of the arrival of the southwest monsoon which prevails for about five months, beginning in early May and ending in late September. The southern area of Taiwan receives 90% of its rainfall between May and October.

      The mountains get the most rain of all in the summer, while places at higher altitudes get very foggy and tend to be drier on the west side than on the east. In the coldest months, snow is visible on the peaks of high mountains (above 3000m/9,840ft).

      The Penghu Islands in the Taiwan Straits are lashed with severe winds during winter. Kinmen and Matsu are surprisingly cold in the winter, due to their proximity to the cooler mainland.