Thai festivals you shouldn't miss! Most festivals depend on the lunar calendar, so the date varies from year to year. Verify the right dates with for example the Tourism Authority of Thailand.
Songkran (Thai New Year) (สงกรานต์)
All Thai people get 2-3 days holidays for their new year. Traditionally Buddha statues are bathed and elders are sprinkled with water to show respect. These days there is more water around. The streets are filled with people smearing white paste on each others faces and throwing water at every passer-by. You will get wet wet and wet. Khao San in Bangkok is a favourite place to go and see how it works, but Chiangmai is the place to be. People put big hose pipes in the khlong (canal) and never stop spraying. Pickup trucks with big water tanks are driving around town doing the same thing. Since it is at the height of the hot season, it is actually quite nice the first day, but like me you'll probably get bored on the second and annoyed on the third day. [13-15 April, most famous in Chiangmai; later that month in Pattaya and Prapadaeng]