Tainan is south of the Tropic of Cancer. Like most of Taiwan, it has a subtropical climate, but Tainan borders on a tropical wet-dry sub-climate. It enjoys a mild and dry climate in the winter. December and January are particularly free of rain, and blue skies can last for weeks throughout the winter. November, December, March and April are usually the most pleasant months for most people. Temperatures in January and February can sometimes dip down below 10°C (50°F) for a few days (which feels colder than it sounds due to humidity), though there can just as easily be daytime highs around 25°C (77°F).
Jackets and sweaters are necessary for cooler days and nights. Summers can be insufferably hot and humid. The heat cranks up to the thirties (90-100°F – which feels hotter than it sounds due to humidity) around mid-May and stays there until mid-October. The summer is also the wet season and rains are more frequent. Typhoon season is also at this time. Typhoons usually occur between June and November, with the highest number of weather watches coming in August and September.