Thailand has three basic seasons. The seasons for each location within Thailand varies a bit, but generally they are as follows.
Seasons in Thailand
•Hot/Dry - March to May*
•Rain - June to October*
•Mild - November to February
Thailand's Rainy Season
Some call this the "Hot & Wet" season. The period of time just before a rainstorm can be especially uncomfortable because of temperature & humidity along with the absense of cooling breezes.
Coastal areas and islands may be a bit more temperate, but escaping the heat is not absolute. A shady spot and cool drink is highly recommended. Thailand definately offers some rainy season advantages
When does Thailand's rainy season actually start? In the North, it starts in June. The beginning and ending of the rainy season tends to migrate from Northern Thailand to Southern Thailand with a difference of about one month.
What that means, the rainy season in the North usually ends a month sooner than it does in the South. But then there is a complication in the South .. two rainy seasons.
Should the rainy season in Thailand be avoided? Definitely not. You can look forward to:
1) Cooler weather
2)Excellent white water rafting or river rafting
3)Fresh air and green flora
4) Avoiding the tourist surge
5)Cheaper & more available accommodations
So actually planning your travel in Thailand during the rainy season has many advantages. The rainfall washes the dust off the trees and grass and bamboo. The bush is verdant .. rice fields a dazzling green. You awaken to an uncommon freshness in the air.