Is September a good month to visit Thailand? Because September is rainy season in Thailand, most parts of the country experience heavy rain. Flooding can be a problem in Bangkok. So you might have to set aside time for indoor activities. However, you can expect discounts at hotels and resorts – if you don’t mind the rain. Are there any parts of the country where rain is less likely?
Last updated: 23 December 2025
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Weather in Thailand in September
How is the weather in Thailand in September? In fact, September tends to be the rainiest month of the year in Thailand. Thunderstorms are common. And humidity is at its peak.
However, it is also one of the coolest months. of the year. Bangkok has an average of 22 rainy days in September, with an average of 8.66 inches (220 millimeters) of rainfall.
And the Thai capital occasionally experiences flooding in parts of the city. Thailand’s second largest city, Chiang Mai, fares a bit better, with an average of 190 millimeters of rainfall in September.
Regarding beach resorts, you can expect heavy rains in Khao Lak, Krabi, and Phuket, which averages 400 millimeters (16 inches) of rain in September. Â And even Khao Sok and Koh Pha Ngan, which tend to be sunny in August, start to experience heavy rains in September.
But this might be good news for events organizers, whose meetings and other activities usually take place indoors. If you want to organize an event, You can expect a warm welcome at beach resorts during rainy season!
Recommended September Beach Resorts
In fact, it’s impossible to guarantee sunshine anywhere in Thailand in September. But if Khao Lak, Khao Sok, Koh Pha Ngan, Krabi, and Phuket tend to be rainy, your chances of sunny days are higher in Cha Am and Hua Hin, which face the Gulf of Thailand.
And the same goes for Koh Samui, an off-shore island located within the Gulf of Thailand. Located 73 miles (117 kilometers) south of Bangkok, Cha Am averages 18 rainy days with 5.28 inches (165 millimeters) of rainfall.
Meanwhile, Hua Hin – which is 124 miles (200 kilometers) south of Bangkok – averages 17 rainy days with 4.72 inches (120 millimeters) in September.
Located 470 miles (755 kilometers) south of Bangkok, Koh Samui also averages just 17 rainy days with 5 inches (130 millimeters) of rain in September.
But keep in mind that rainfall tends to increase as the month progresses. If rain doesn’t bother you, September could be one of the best times to visit Thailand.
You can shop till you drop at Bangkok’s tony shopping malls. And a little rain won’t hurt you if you want to indulge at a sybaritic spa treatment. Because it is off-season, many hotels and resorts offer discounts in September. And for events organizers, whose events usually take place indoors, that can be good news.
Thailand September Events
IT&CMA Asia presents unparalleled networking opportunities for MICE professionals in the Asia-Pacific region. Photo Credit: TTG Asia Media.
As one of the rainiest months of the year, September in Thailand is a relatively quiet month. However, there are a couple of holidays and important travel-related trade fairs. And there’s always the monthly full moon party at Haad Rin.
Phichit Boat Racing Festival – 18 September 2026
A total of 40 traditional long boats will compete in the Phichit Boat Race. And they will be divided into four categories. To clarify, they take place when rivers are at their highest level.
Meanwhile, vendors will be peddling a variety of local products. And they will include such horticultural products as guava, pomelo, tamarind sweets, and other organically grown fruits and vegetables.
In addition, there will be tamarind sweets and local handicrafts. The races usually take place in the first week of September.
Phichit is a province in lower northern Thailand. It is about 330 kilometers north of Bangkok.
Sart Thai Festival – 19 September 2026
The Sart Thai Festival (Ancestor Day) is dedicated to honoring deceased relatives and ancestors. The festival blends ancient harvest rituals with Buddhist merit‑making practices.
Families gather at temples to offer food, rice, and fruit to monks, while ceremonies of remembrance express gratitude to past generations.
Particularly significant in Central and Southern Thailand, Sart Thai reinforces family bonds and cultural continuity through acts of respect and generosity.
It is observed on the new moon of the 10 month on the Thai Lunar Calendar.
Future Dates
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2027: 9 October
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2028: 26 September
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2029: 16 September
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2030: 4 October
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2031: 23 September
IT & CMA Asia – 22to 24 September 2026
IT & CMA Asia – Incentive Travel & Conventions, Meetings – is a leading trade fair for MICE professionals, a.k.a. meetings, incentives, conferences, and exhibitions. There will more than 900 exhibitors. And tens of thousands of attendees are expected.
Running concurrently with IT & CMA Asia, CTW Asia Pacific – Corporate Travel World Asia Pacific – is an important conference for corporate travel management professionals in the Asia Pacific region.
To clarify, it aims to promote best practices in the travel and entertainment sector.
Bangkok Convention Centre (BCC) – CentralWorld, 999/99 Rama 1 Road, Pathumwan, Bangkok, Thailand.
Mahidol Day – 24 September 2026
The grandfather of His Majesty King Rama X, Prince Mahidol is honoured as the Father of Modern Thai Medicine on Mahidol Day. Mahidol was the father of King Ananda Mahidol (Rama VIII) and King Bhumibol Adulyadej (Rama IX) of Thailand, and the paternal grandfather of King Vajiralongkorn (Rama X). Future Dates
- 24 September 2026
Full Moon Party – 26 September 2026
The Full Moon Party is held on the beach of Haad Rin every month on the night of the full moon. DJs play a variety of musical styles including trance, dubstep, reggae, and techno. Jugglers, fire-eaters, and fireworks add drama to the all-night event.
Haad Rin is crescent shaped beach located on the island of Ko Pha Ngan. It can be reached by boat from Koh Samui, an island off the coast of Southern Thailand.
Koh Samui is 293 miles (471 kilometres) south of Bangkok. Because the drive takes nearly 10 hours, air travel is recommended,. The flight takes just over one hour.
Thai National Flag – 28 September 2026
Flag Day was established in 2016 to celebrate the adoption of the national flag of Thailand by King Vajiravudh (Rama VI) in 1917.
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