Weather in Tainan

Tainan is in Taiwan at 23.0°N. The 2001–2020 NASA POWER daily record describes a monsoon climate with a sharp wet-dry split. July is the warmest month (average 29.0°C, high 30.0°C) and January is the coolest (average 20.0°C, low 18.2°C).

Rain is the monsoon runs from May to September, inside an annual total of 1892 mm. The wettest month is August at 442 mm; the driest is February at 31 mm. On this site the months that score closest to a 22°C day, lighter rain, and moderate humidity are December, January, and February.

Temperature through the year

Monthly average highs run from 21.8°C in January to 30.0°C in July. Nights follow the same curve: 18.2°C in January and 27.9°C in July.

Across the year the mean afternoon high is 26.6°C. If you want the smallest day–night shock, look at months where the high and low sit close together; July nights still hold 27.9°C.

Rainfall pattern

The monsoon in Tainan starts in May and ends in September (May, June, July, August, and September). August is the core of it at 442 mm. February is the other extreme, with 31 mm.

Humidity peaks near 85%. That usually lines up with the wetter months rather than the hottest ones.

What stands out month by month

The year bottoms out in January. Plan for 18.2°C at night and 21.8°C in the afternoon. February is the driest month, averaging only 31 mm across 8 rainy days. Highs sit near 22.8°C. The monsoon opens in May. Expect 223 mm and 17 rainy days, with nights around 25.7°C. In June, Tainan averages 29.3°C by day and 27.3°C at night, with 344 mm of rain.

Peak heat arrives in July: 30.0°C by day, 27.9°C at night, and 83% humidity. August is the wettest month — 442 mm and 21 rainy days, with 84% humidity. By September the monsoon is ending. Tainan still sees about 242 mm, but the next month is usually leaner. October: 27.8°C high, 25.1°C low, 72 mm rain, 80% humidity.

When the score favours a visit

The three months with the highest comfort score are December, January, and February: December (21.5°C average, 34 mm, 77% humidity); January (20.0°C average, 39 mm, 77% humidity); February (20.8°C average, 31 mm, 78% humidity). Those months sit across the year end, so they are listed in season order rather than January-to-December. The score rewards averages near 22°C, lower rainfall, and humidity near 60%. It is a climate score, not a festival or price calendar.

If you want the monsoon itself — fewer crowds, greener landscape, heavier rain — aim at May–September instead of the score.

Tainan and other cities in Taiwan

Kaohsiung is about 43 km away: Tainan is about as warm as Kaohsiung at the hot peak and 253 mm wetter over the year than Kaohsiung. Kaohsiung’s wettest month is August (403 mm) versus August here.

Taichung is about 137 km away: Tainan is 1.6°C warmer than Taichung in its hottest month and 154 mm wetter over the year than Taichung. Taichung’s wettest month is August (329 mm) versus August here.

Taipei is about 265 km away: Tainan is 1.1°C warmer than Taipei in its hottest month and a similar annual rainfall (1916 mm in Taipei). Taipei’s wettest month is June (270 mm) versus August here.