September is the peak of the rainy weather in Thailand. September is one of the months from where you will observe a slight increase in temperature and high level of humidity. However, rain usually comes in short, intense bursts, followed by periods of sunshine. The average temperature in Thailand is between 25°C to 32°C which also indicates a slight increase in temperature. Despite the rainfall there is a good amount of sunshine for about 3 to 6 hours with 80 to 90% of humidity level.
Overview of Thailand’s Weather in September 2025
| Season | September is the peak of the rainy (monsoon) weather in Thailand. |
| Temperature | In September, the temperature usually stays between 25°C to 32°C, offering warm and pleasant days in Thailand. |
| Rainfall | Frequent rain showers are common, especially in the afternoons and evenings, ranging between 300-400 mm during the month of September. |
| Sunshine | Sunshine is limited, with most places getting around 3 to 6 hours of sunlight each day. |
| Humidity | Humidity levels are very high, often between 80% to 90%, which can feel sticky. |
What’s the weather like in Thailand in September?
In the month of September you will experience slightly warmer temperature as compared to the month of July. The average temperature falls between the range of 25°C to 32°C during the day time whereas at night the temperature falls to 25°C. The temperature can vary from one region to another. In the northeast places like Bangkok and Chiang Mai the highest temperature can go up to 33°C and in the night the temperature can fall to 24°C. However, in mountainous regions like Chiang Rai and Mae Hong Son the temperature is much cooler making it an ideal destination to visit.
Since September is a part of the rainy season people hesitate to visit Thailand during this time. However, it can be an good time to visit for people who want less crowd and want to spend some time in peace in the wanderlust land of Thailand.
Thailand Weather in Different Months
What to Expect in August
September is not considered the best time to visit Thailand, but it can still be a good choice if you’re flexible and want to avoid crowds. September is a peaceful and pocket-friendly time to explore Thailand if you don’t mind a little rain. For the best weather, November to February is ideal, but if you’re okay with monsoon vibes and lush greenery, September is still a good choice.
Average daily temperatures in September
The weather in Thailand is warm and humid during the month of September but it may vary from region to region. The central Thailand is hot during the daytime however receives heavy rainfall in the evening. Southern Thailand is hot and humid throughout the month while Northern Thailand receives heavy rainfall which decreases as the month progresses The Mountainous areas like Chiang Rai and Mae Hong Son witness a drop in the temperature.
Sunshine
Despite the heavy rainfall in certain parts of Thailand there is still little sunshine which stays for 6 hours in a day. You might not be able to enjoy the water activities due to sea conditions. However, you can plan a visit to the major attractions in the morning time when there is less sunshine and rainfall as compared to the evening time.
Rainfall
In August most of the country receives heavy rainfall throughout Thailand of an average about 150mm. However, the rainfall varies from region to region with some areas like the Chiang Mai and Sukhothai receiving more rainfall. Areas like Bangkok and Ayutthaya also receive moderate amounts of rainfall.
Is September a good time to visit Thailand?
Yes, September is a good time to visit Thailand if you do mind slight rain. Also it is ideal because there is less crowd and fares of almost everything are down due to the off season period. You will experience rain in the south which is in short bursts rather than heavy downpour. While in Northern Thailand you will witness much cooler temperatures.
Pros and Cons of Visiting Thailand in September
| Pros | Cons |
|---|---|
| You can immerse in local festivals like the Vegetarian Festival in Phuket. | Although there is less rainfall but the humidity level is quite high. |
| September is off peak season which can lead to less crowd so you will be able to enjoy more. Fares of most of the things will be lower compared to other months. | Most of the places will be shut due to heavy rainfall. |
| The rain leaves behind the lush green landscapes which you can enjoy. | The roads are not in good condition which can lead to accidents. |
All Your Questions Answered
The weather in Thailand is hot and humid with sudden heavy downpours in the evening time.
Yes, September is the wettest month and it rains like cats and dogs in the month of September.
In September, the Gulf islands like Koh Samui, Koh Pha-Ngan, and Koh Tao generally offer the best weather balance.
It is preferable to carry light breathable clothes and is best to carry an umbrella or raincoat.
No, Thailand is not crowded during September.
