There is no single best month for all of Thailand. In Bangkok and Chiang Mai, the most comfortable months are November to February: little rain and cooler nights, and in Bangkok the lowest humidity of the year. On Phuket and the Andaman coast, December to March is the driest time. Koh Samui and the Gulf-side south are different: October to December is the wettest time there, and February to September is the drier stretch.
Temperatures and rainfall below are 1991–2020 averages from Thai Meteorological Department (TMD) station data. They describe a typical year, not a forecast.
The short answer by region
| Region | Best months | Wettest months | Watch out for |
|---|---|---|---|
| Bangkok | November–February | September, October | Heat in April |
| Chiang Mai and the north | November–February | August, September | Smoke and haze in March and April |
| Phuket and the Andaman coast | December–March | September, October | Similan Islands closed mid-May to mid-October |
| Koh Samui and the Gulf-side south | February–September | October–December | Flood risk in November and December |
| Pattaya | November–April | September, October | Rainy-season showers, peaking in October |
Thailand's three seasons
Cool season: mid-October to mid-February
In Bangkok, December is the least humid month of the year (65.6%), and average daily highs in December and January are 32.3–32.7°C. In Chiang Mai, nights are genuinely cool: the average January low is 15.7°C. On the highest mountains it can freeze. On 27 November 2025, the summit of Doi Inthanon was 2°C, with −2.3°C at the coldest point.
Hot season: mid-February to mid-May
Typical hot-season highs are 35–39°C, and the hottest days go above 40°C. April is Bangkok's hottest month, with an average high of 35.7°C; 40°C in Bangkok is possible but rare. Chiang Mai is even hotter in April (average high 36.7°C).
The hot season is still good beach weather on both coasts. Drink water often, rest in the shade or air conditioning at midday, and call 1669 for heat stroke (confusion, hot and dry skin).
Rainy season: mid-May to mid-October
TMD declared the 2026 rainy season officially started on 15 May 2026. It forecast rainfall about 10% below normal for 2026, with the heaviest rain and the highest flash-flood risk in August and September. It expects the rains in upper Thailand to end around mid-October 2026, while on the Gulf side of the south the rain continues until December.
Rain does not usually last all day. Even in September, Bangkok's wettest month, there are about 18 days with rain, so many days stay partly dry. Plan outdoor sightseeing for the morning, keep indoor options for later in the day, and do not wade or drive through floodwater.
Best times by region
Bangkok
November to February is the most pleasant time in the capital, with only 11.6 mm of rain in December and 23.6 mm in January. The rain peaks in September (335.9 mm) and October (288.7 mm). Fixed transfer fares from Suvarnabhumi and Don Mueang airports are on the list of all Smile Taxi Service routes and fares.
Chiang Mai and the north
The north has the clearest contrast between seasons. From November to February the days are warm (average highs of 29.2–30.8°C from November to January) and the nights are cool, with rainfall of just 11.3 mm in January and 9.6 mm in February. Bring a warm jacket if you plan to visit Doi Inthanon, Thailand's highest peak at 2,565 m: mountain mornings from December to January can be near or below freezing, and the summit road can be slippery with frost.
March and April are hot and often smoky. In April 2026, Chiang Mai had the world's worst air quality and was declared a disaster zone for air pollution. In these months, check PM2.5 levels on the free Air4Thai or IQAir AirVisual apps before planning outdoor days.
The rains come from May, and August is the wettest month (223.3 mm). The Kew Mae Pan nature trail on Doi Inthanon is closed from June to October and reopens on 1 November; the summit, chedis and waterfalls stay open.
To get north, read how to get from Bangkok to Chiang Mai and how to get from Bangkok to Chiang Rai.
Phuket and the Andaman coast
December to March is the classic beach season on the west coast. February is the driest month in Phuket, with about 24 mm of rain on only 2.2 rain days.
From May the south-west monsoon brings heavy rain; September (350.4 mm) and October (336.0 mm) are the wettest months. The Similan Islands and Maya Bay close for part of the rainy season (see "Best times by activity" below). See how to get from Bangkok to Phuket.
Koh Samui and the Gulf-side south
On Koh Samui, February (64.3 mm) is the driest month, and February to September is the drier stretch. The wet peak is October to December: 294.9 mm in October, 444.6 mm in November and 263.1 mm in December. January is still fairly wet (126.8 mm).
From October to December, keep a few spare days in your plans for Samui, Nakhon Si Thammarat and Songkhla. In late November 2025, Cyclone Senyar flooded southern Thailand, and Songkhla, where Hat Yai is, was hit hardest. See how to get from Bangkok to Koh Samui.
Pattaya
Pattaya is drier than Bangkok, with about 1,106 mm of rain a year compared with 1,702 mm. November to April is the drier part of the year (16.3 mm in January), and October is the wettest month (224.5 mm). See how to get from Bangkok to Pattaya.
Best times by activity
Beaches, diving and snorkelling
For boat trips on the Andaman coast, two closures matter:
- Similan Islands: Mu Ko Similan National Park is open from 15 October to 15 May and closed from 16 May to 14 October. The 2026–27 season opens on 15 October 2026.
- Maya Bay: the bay on Koh Phi Phi Le closes every year from 1 August to 30 September for reef recovery and reopens on 1 October. Phi Phi boat tours keep running during the closure but may not enter the bay.
In all marine national parks, sunscreen with oxybenzone and other chemicals that harm coral is banned (since August 2021), with fines of up to 100,000 THB. Bring a sunscreen without oxybenzone.
Hiking and mountains
November to February, with dry days and cool nights, is the best time for hiking in the north. Some trails and parks close in the rainy season: besides the Kew Mae Pan trail, Phu Kradueng National Park in Loei closes from June to September every year (park information checked in September 2026). Confirm with the Department of National Parks, hotline 1362, before you go.
Temples and city sightseeing
You can visit temples all year, but November to February is the most comfortable time for long walks. At the Grand Palace in Bangkok, cover your shoulders and knees (no shorts or sleeveless tops). The palace is open daily from 08:30 to 16:30, and ticket sales close at 15:30.
Festivals and dates to plan around
| Date | Event | Where |
|---|---|---|
| About 10–18 October 2026 | Vegetarian Festival | Phuket Old Town |
| 12–16 October 2026 | IMF / World Bank meetings; 16 October is a Bangkok holiday | Bangkok |
| 26 October 2026 | End of Buddhist Lent (Ok Phansa) | Nationwide |
| 24 November 2026 | Loy Krathong | Nationwide |
| About 23–25 November 2026 | Yi Peng and Loy Krathong events | Chiang Mai |
| 15–19 December 2026 | Royal cremation ceremonies for Queen Sirikit The Queen Mother | Sanam Luang, Bangkok |
| 6 February 2027 | Chinese New Year | Yaowarat (Chinatown), Bangkok |
| 5–7 February 2027 (expected) | Flower Festival | Chiang Mai |
| 13–15 April every year | Songkran | Nationwide |
The royal cremation itself is on 16 December 2026 at Sanam Luang, next to the Grand Palace. In Chiang Mai, the big lantern releases are ticketed events at licensed venues outside the city. The Flower Festival dates for 2027 are not yet official.
Getting around, whatever the season
Smile Taxi Service fares do not change with the season or the weather. Every fare is fixed, per vehicle (not per person) and one way, with expressway tolls included and no meter. Some examples:
| Route | Sedan | SUV | Van |
|---|---|---|---|
| Suvarnabhumi Airport to Bangkok | 600 THB | 800 THB | 1,100 THB |
| Suvarnabhumi Airport to Pattaya | 1,200 THB | 1,500 THB | 1,800 THB |
| Phuket Airport to Patong Beach | 1,000 THB | 1,100 THB | 1,400 THB |
| Suvarnabhumi Airport to Chiang Mai | 7,500 THB | 8,500 THB | 10,000 THB |
| Chiang Mai to Chiang Rai | 2,500 THB | 3,000 THB | 3,800 THB |
Airport pickups include 60 minutes of free waiting from the actual landing time, and a person checks your flight. You pay the driver in cash (THB) at the end of the trip; if you can only pay by card, message the team for a PayPal payment link (a 5% fee is added). Cancellation is free up to 24 hours before pickup. After that, a cancellation or change costs 25% (less than 24 h), 35% (less than 12 h) or 50% (less than 2 h) of the price, and a no-show 100%, also when you pay the driver in cash (details).
For a cool-season day in the mountains, the full-day Chiang Mai + Doi Tour (up to 10 hours) costs 3,300 THB by sedan, 3,500 THB by SUV, 4,000 THB by van and 4,500 THB by VIP van. See private tours and day trips.
Useful phone numbers
- Tourist Police: 1155
- Medical emergency: 1669
- Police and general emergency: 191
- TMD weather hotline: 1182
- DDPM disaster hotline (Department of Disaster Prevention and Mitigation): 1784
- TAT call centre (Tourism Authority of Thailand): 1672
If a T-Alert warning (Thailand's national phone alert system) appears on your phone, follow its instructions.
FAQ
When is the rainy season in Thailand? Officially from mid-May to mid-October; in 2026 it began on 15 May. On Koh Samui and the Gulf side of the south, the rain lasts until December.
What is the best month for Phuket beaches? December to March. February is the driest month, with about 24 mm of rain.
Is Koh Samui's weather the opposite of Phuket's? Largely, yes. Phuket is wettest from August to October, while Samui is wettest from October to December, with 444.6 mm in November.
Are there dates to avoid in Bangkok in late 2026? Around 12–16 October (IMF / World Bank meetings; 16 October is a Bangkok holiday) and 15–19 December (the royal cremation ceremonies at Sanam Luang). Expect security checks, crowds and road closures.
Do I need warm clothes? Only for the north and the mountains from about November to February. Chiang Mai averages 15.7°C at night in January, and high summits can drop below 0°C.
Where can I check the weather and air quality? TMD's free "Thai Weather" app or its hotline, 1182, for forecasts, and Air4Thai or IQAir AirVisual for PM2.5.
Planning a trip in any season? Message us on WhatsApp or LINE, or open the booking page.