Taipei’s high season includes February’s Lunar New Year as well as the late-spring and summer months, May through August. The Taiwanese typically get a week of vacation in February to celebrate the Lunar New Year, meaning train and bus travel around the island can get pretty busy during this time.
Additionally, because Taiwan’s academic calendar is similar to that of the United States, many Taiwanese students and families take advantage of the extended summer breaks to travel and sightsee, making tourist hot spots such as Taipei 101, the National Palace Museum, and Shilin Night Market extra crowded. Add the high temperatures and extreme humidity of the season and summers are arguably one of the worst times to visit Taipei.
Low season is January to April, excluding Lunar New Year in February, and October to November. While the weather is still very hot into October, the temperatures in November through April are much cooler, in the low 60s. Be mindful that Taiwan is a tropical island and experiences typhoon season between the months of June and October.
Ultimately, the best time to visit Taipei would be before May and after September to avoid the summer heat. Since these times coincide with low season, it’s pretty much a win-win for travelers interested in visiting the island.