Thailand’s climate varies greatly depending on the region. The graph below gives an indication of average temperatures and rainfall in the southern area.
Thailand´s monsoons arrive around July and last into November (the ´rainy season´). This is followed by a dry, cooler period from November to mid-February, followed by much higher relative temperatures from March to June.
There is no real bad time to go, especially in the south, but generally speaking December to May would be considered the best time.
Jan Feb Mar Apr May Jun
Temp (°C) 26 27 28 29 29 28
Rainfall (mm) 130 70 75 80 145 110
Jul Aug Sep Oct Nov Dec
Temp (°C) 28 28 27 27 26 26
Rainfall (mm) 115 112 112 300 490 210