Bangkok is hot in every month of the year, and its seasons are defined by rain and humidity rather than by temperature: a dry, slightly cooler spell from November, a fierce hot season in spring and a long monsoon from May to October. The clock is simpler, running on UTC+7 all year with no daylight saving.
Climate overview
Bangkok sits on the flat delta of the Chao Phraya River, barely above sea level and close to the Gulf of Thailand. It has a tropical savanna climate (Köppen Aw): hot all year, with a pronounced wet season and dry season.
Average highs stay between 32°C and 36°C in every month, and the average low never falls below 23°C. The difference between the "cool" and the hot season is a few degrees and a big change in humidity, not a change of wardrobe.
Annual rainfall is about 1,702 mm, most of it falling between May and October during the south-west monsoon. September is the wettest month with 336 mm, while the months from December to February get very little. The city gets around 2,212 hours of sunshine a year, with the brightest skies in the dry months from November to April.
Thais traditionally divide the year into three seasons: a cool, dry season from November to February, a hot season from March to May and a rainy season from June to October, with May as the hinge between the last two.
Bangkok through the seasons
Cool season (November to February)
This is the most comfortable time of year. Highs stay around 32–34°C, but nights are the coolest of the year, at around 23°C in December, and the air feels noticeably drier. Rain is rare: December is the driest month of the year, with just 12 mm. Skies are often clear. Air quality can deteriorate from January to March because of agricultural burning in the surrounding provinces and traffic in the city.
Hot season (March to May)
Temperatures peak in April at about 36°C, with very warm nights near 27°C. Humidity rises, and the heat index on a still afternoon is well above the air temperature. Songkran, the Thai New Year in mid-April, is celebrated with citywide water fights, a welcome way to cool off. The first big storms usually arrive in May, when rainfall jumps to 217 mm.
Rainy season (June to October)
The south-west monsoon brings regular afternoon and evening downpours, often heavy but short and followed by sunshine. Rain falls on around 18 days in September, the peak of the season, and October is almost as wet. Street flooding is common after big storms. Temperatures ease slightly, with highs around 33–34°C, and the cloud cover means the rainy months are the least sunny of the year.
What makes Bangkok's weather distinctive
Bangkok's low elevation and the flat river delta make flooding a recurring challenge. A heavy storm can flood streets within an hour and slow traffic to a crawl, though the water usually drains within hours. In 2011, exceptional monsoon rains caused severe flooding across central Thailand and affected parts of the city for weeks. The ground beneath Bangkok is also slowly sinking, which adds to the long-term flood risk.
Heat and humidity are constant. Even in the cool season the midday sun is strong, and from March to May heat-related illness is a real concern for visitors who walk a lot. Plan sightseeing for early mornings and late afternoons, drink more water than you think you need, and use air-conditioned transport such as the BTS Skytrain and MRT to get across town.
Rain in Bangkok is usually intense rather than prolonged. Even in September it is rare for a whole day to be lost to rain; the typical pattern is a dramatic storm in the late afternoon or evening, then clearer skies. You can watch the live situation on our Weather page.
Best time to visit Bangkok
November to February is the best time to visit, with lower humidity, cooler nights and very little rain. It is also the peak tourist season, so book popular hotels early, especially around Christmas and New Year.
March to May is very hot, but it is a good time for Songkran and for visitors who handle heat well. June to October is rainy but greener and less crowded, with hotel prices lower and storms usually limited to a few hours a day. If you are combining Bangkok with Thailand's beaches, check the regional pattern: the Gulf islands and the Andaman coast have their rainy peaks at different times of year.
What to pack
- Light, breathable clothing in natural fabrics
- Clothing covering shoulders and knees for temples such as Wat Phra Kaew and the Grand Palace
- A compact umbrella or rain poncho, especially from May to October
- Sunscreen, a hat and insect repellent
- Sandals or quick-drying shoes for flooded streets
- A light layer for heavily air-conditioned malls, trains and cinemas
Time in Bangkok
Bangkok uses the Asia/Bangkok time zone at UTC+7 all year; Thailand does not observe daylight saving time, so the offset never changes. At the moment Bangkok is 7 hours ahead of London; because the UK changes its clocks and Thailand does not, the gap with London is one hour smaller in the northern summer than in winter. The same zone is shared by Vietnam, Cambodia and western Indonesia, including Jakarta. Thailand has kept UTC+7 since 1920, when it replaced local Bangkok mean time.
| With | Difference | Time in Bangkok | Their time |
|---|---|---|---|
| London | −7 h | 16:00–18:00 | 09:00–11:00 |
| New York | −12 h | No overlap | – |
| Dubai | −3 h | 12:00–18:00 | 09:00–15:00 |
| Tokyo | +2 h | 09:00–16:00 | 11:00–18:00 |
| Sydney | +4 h | 09:00–14:00 | 13:00–18:00 |
| Date | Sunrise | Sunset | Day length |
|---|---|---|---|
| 20 March | 06:22 | 18:28 | 12 h 6 min |
| 21 June | 05:51 | 18:47 | 12 h 56 min |
| 22 September | 06:07 | 18:14 | 12 h 7 min |
| 21 December | 06:36 | 17:55 | 11 h 18 min |
Frequently asked questions
What is the hottest month in Bangkok?
April, with average highs of 36°C and warm, humid nights. March and May are only slightly cooler.
When is the rainy season in Bangkok?
From May to October. September is usually the wettest month, with around 336 mm of rain on average.
Is Bangkok cool in winter?
Not by European standards: December and January highs are still around 32–33°C. Nights are cooler and the air drier, though, so it feels far more comfortable than the rest of the year.
Does Bangkok flood every year?
Short-lived street flooding after heavy storms happens most rainy seasons. Serious, prolonged flooding like that of 2011 is much rarer.
Does Thailand change its clocks?
No. Thailand stays on UTC+7 all year round.