Country guide
Thailand weather by month
January and February are the strongest starting points for a Thailand holiday built around outdoor time. February has the fewest rain days at 5, with daytime temperatures averaging 31°C, while January is slightly cooler. Sea temperatures stay at 28°C or above throughout the year, so rain is more useful than water warmth when choosing beach dates. For cities, favour the cooler start or end of the year and leave room for breaks from the midday heat.
- Hottest month
- 32.1°CApril
- Coolest month
- 28.6°CDecember
- Warmest sea
- 30.3°CMay
- Destinations tracked
- 6warmest: Bangkok
Thailand, month by month
A little perspective
Thailand through the year
Country figures are the mean of the 6 destinations listed below; individual resorts can differ by several degrees.
| Month | Day | Night | Sea | Sun/day | Rain mm | Rainy days | Days 25°C+ |
|---|---|---|---|---|---|---|---|
| Januarybest | 29.2°C | 22.6°C | 27.9°C | 5.6 | 44 | 7 | 98% |
| Februarybest | 30.7°C | 23.5°C | 28.4°C | 6.5 | 28 | 5 | 100% |
| March | 31.8°C | 24.8°C | 29.3°C | 6.2 | 75 | 9 | 100% |
| April | 32.1°C | 25.9°C | 30.2°C | 4.9 | 112 | 15 | 100% |
| May | 30.9°C | 25.9°C | 30.3°C | 2.5 | 198 | 23 | 100% |
| June | 30.1°C | 25.7°C | 29.8°C | 1.6 | 191 | 22 | 100% |
| July | 29.6°C | 25.4°C | 29.4°C | 1.5 | 204 | 23 | 100% |
| August | 29.2°C | 25.2°C | 29.1°C | 1.4 | 231 | 24 | 100% |
| September | 29.0°C | 24.8°C | 29.0°C | 1.6 | 268 | 25 | 100% |
| October | 28.7°C | 24.1°C | 29.0°C | 2.3 | 267 | 25 | 99% |
| November | 28.9°C | 23.5°C | 28.8°C | 3.7 | 163 | 17 | 99% |
| Decemberbest | 28.6°C | 22.6°C | 28.2°C | 4.5 | 79 | 10 | 97% |
Day = average daytime high, night = average night-time low, 1991-2020.Sun is hours per day; rainy days count 1 mm or more.
Day, night and sea
Monthly average temperatures, 1991-2020
- Day
- Night
- Sea
When to go to Thailand
Daytime highs average 25°C or more in January, February, March, April, May, June, July, August, September, October, November, December. The sea reaches a swimmable 22°C from January to December. Winter (December to February) averages 30°C by day - genuine winter sun. September is the wettest month (268 mm) and February the driest (28 mm).
Destinations in Thailand
Each has a 12-month table; our most searched places have month-by-month detail pages.
| Destination | Hottest month | Coolest month | Months 25°C+ | Sea (warmest) | Flight from London |
|---|---|---|---|---|---|
| Phuket | March 30°C | October 28°C | 12 | 30°C | 13 h 6 min |
| Koh Samui | May 30°C | January 28°C | 12 | 31°C | 13 h 6 min |
| Bangkok | April 35°C | October 31°C | 12 | 31°C | 12 h 42 min |
| Krabi | March 32°C | September 29°C | 12 | 30°C | 13 h 12 min |
| Khao Lak | March 31°C | September 28°C | 12 | 30°C | 13 h 6 min |
| Chiang Mai | April 36°C | December 27°C | 12 | - | 12 h |
Warmest place in Thailand each month
| Month | Warmest destination | Day | Coolest destination | Day | Warmest sea |
|---|---|---|---|---|---|
| January | Bangkok | 31°C | Koh Samui | 28°C | Khao Lak 28°C |
| February | Bangkok | 32°C | Koh Samui | 28°C | Khao Lak 29°C |
| March | Chiang Mai | 34°C | Koh Samui | 29°C | Krabi 30°C |
| April | Chiang Mai | 36°C | Phuket | 30°C | Krabi 30°C |
| May | Bangkok | 33°C | Phuket | 29°C | Bangkok 31°C |
| June | Bangkok | 32°C | Phuket | 29°C | Bangkok 30°C |
| July | Bangkok | 32°C | Phuket | 29°C | Krabi 30°C |
| August | Bangkok | 31°C | Phuket | 28°C | Bangkok 29°C |
| September | Bangkok | 31°C | Phuket | 28°C | Bangkok 29°C |
| October | Bangkok | 31°C | Phuket | 28°C | Bangkok 29°C |
| November | Bangkok | 31°C | Koh Samui | 28°C | Krabi 29°C |
| December | Bangkok | 31°C | Chiang Mai | 27°C | Khao Lak 29°C |
The shape of the year
Thailand stays warm throughout the year; the bigger change is how often rain affects your plans. January and February offer the clearest balance of warmth and fewer wet days. March brings hotter days and a modest increase in rain, before April reaches 32°C by day and 26°C at night, with 15 rain days. From May, frequent rain becomes the main planning constraint. September and October have the most rain days, at 25, so fixed outdoor schedules are a poor fit. November starts the shift towards less frequent rain, and December offers a cooler, less wet option, though neither is as dry as February.
Choosing between destinations
Bangkok is the warmest destination across the year, averaging about 32°C by day, while Phuket is the coolest at about 29°C. That makes Phuket cooler in relative terms, not a place to expect cool afternoons. Bangkok calls for light clothing and regular breaks from the heat; Phuket still needs the same basic preparation. For beach choices among Phuket, Krabi, Khao Lak and Koh Samui, do not treat the national monthly pattern as a guarantee of matching conditions. Local rain timing is the important detail to check before settling on dates. Chiang Mai also needs its own monthly check rather than assumptions based on beach weather.
When to go for beaches or cities
For a beach-led trip, start with January or February, then check the pattern for your chosen destination. The sea averages 28°C in both months, so there is little reason to choose a hotter, wetter month simply for warmer water. March is an option if you can accept more heat and rain. For Bangkok or Chiang Mai, January and December are sensible starting points for a cooler-weather search, rather than a promise of cool city days. In the wetter months, keep outdoor plans movable and carry a light waterproof. Nights remain warm nationally, so prioritise light clothing rather than packing for a sharp evening chill.
A little more detail
Thailand weather FAQs
Plain answers, grounded in the averages.
When is the best time to visit Thailand?
Weighing warmth, low rainfall and sunshine across 6 destinations, the best months for Thailand are February, January, December. April is the hottest month (average high 32.1°C) and December the coolest (28.6°C).
How many months is Thailand over 25°C?
12 months average a daytime high of 25°C or more across our Thailand destinations.
Which is the hottest place in Thailand?
Over the year, Bangkok has the highest average daytime temperature of the 6 Thailand destinations we track (31.9°C averaged across all months).
Which month has the least rain?
February has the fewest rain days nationally, at 5, followed by January at 7. February is warmer, with average daytime temperatures of 31°C against January's 29°C. Choose January if slightly lower heat matters more to you.
Is the sea warm enough throughout the year?
Average sea temperatures range from 28°C to 30°C, so water warmth is unlikely to be the deciding factor for a beach holiday. Rain deserves more attention when choosing dates. Warm water alone does not tell you about swimming conditions.
Will evenings feel cool?
National average night temperatures range from 23°C to 26°C, so expect warm evenings rather than a marked chill after sunset. April, May and June have the warmest nights. Light, loose clothing is a practical starting point for packing.
About these averages
ERA5-Land climate reanalysis via Open-Meteo (11 km grid), 1991-2020
Averages computed from daily values at 6 destination points.Records are the highest and lowest daily values in that 30-year period, not all-time records. These are climate averages, not a forecast for your trip. How we measure holiday weather
- Hot · 25°C+
- Warm · 20°C to below 25°C
- Mild · 15°C to below 20°C
- Cool · below 15°C