From the meteorological point of view the climate of Thailand may be divided into
three seasons as follows:
- Summer or pre-monsoon season (mid-February to mid-May).
This is the transitional period from the northeast to southwest monsoons.
The weather becomes warmer, especially in upper Thailand. April is the hottest month.
- Rainy or southwest monsoon season (mid-May to mid-October).
The southwest monsoon prevails over Thailand and abundant rain occurs over the country.
The wettest period of the year is August to September. The exception is found in
the Southern Thailand East Coast where abundant rain remains until the end of
the year that is the beginning period of the northeast monsoon and November is
the wettest month.
- Winter or northeast monsoon season (mid-October to mid-February).
This is the mild period of the year with quite cold in December and January in upper
Thailand but there is a great amount of rainfall in Southern Thailand East Coast,
especially during October to November.
For more information: Thai Meteorological Department
