Weather in Bangkok

April is the warmest month (average 31.4°C, high 36.6°C) and December is the coolest (average 25.3°C, low 19.7°C). That 6.1°C swing in monthly averages is the first thing to plan around in Bangkok.

Rain is the monsoon runs from May to October, inside an annual total of 1361 mm. The wettest month is September at 278 mm; the driest is December at 10 mm. Bangkok is in Thailand at 13.8°N. The 2001–2020 NASA POWER daily record describes a monsoon climate with a sharp wet-dry split. 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

Bangkok has a 6.1°C gap between its coolest monthly average (25.3°C in December) and its warmest (31.4°C in April). That is a northern-hemisphere pattern.

Across the year the mean afternoon high is 32.9°C. If you want the smallest day–night shock, look at months where the high and low sit close together; April nights still hold 26.2°C.

Monsoon and dry months

The monsoon in Bangkok starts in May and ends in October (May, June, July, August, September, and October). September is the core of it at 278 mm. December is the other extreme, with 10 mm.

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

The calendar in Bangkok

Peak heat arrives in April: 36.6°C by day, 26.2°C at night, and 66% humidity. The monsoon opens in May. Expect 164 mm and 22 rainy days, with nights around 26.0°C. September is the wettest month — 278 mm and 27 rainy days, with 85% humidity.

By October the monsoon is ending. Bangkok still sees about 203 mm, but the next month is usually leaner. In November, Bangkok averages 30.5°C by day and 21.8°C at night, with 39 mm of rain. The year bottoms out in December. Plan for 19.7°C at night and 30.9°C in the afternoon.

When the score favours a visit

The three months with the highest comfort score are December, January, and February: December (25.3°C average, 10 mm, 71% humidity); January (26.8°C average, 17 mm, 64% humidity); February (29.5°C average, 14 mm, 61% 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–October instead of the score.

Bangkok and other cities in Thailand

Bangkok is the only Thailand city in this dataset, so the figures on this page are the national sample we publish. They still come from the same NASA POWER daily series (2001–2020) used everywhere else on the site.