Thailand enjoys a tropical climate with the distinct seasons, which locals sometimes humorously refer to as "hot" and " hot and wet" and " hot and dry" The "hot" season is actually the country's "cool" season, which low upon the heels of the rainy season and extends from October through February. It's one of the best times to visit.
The "hot and dry" season better known as summer, follows the "hot" season and extends from March through May. This is the season when temperatures reach their highest, generally in April and May.
The "hot and wet" season, more commonly referred to as the rainy season, occurs from June to September when the country is subject to monsoonal weather that brings plenty of rain, especially to the coasts, The average annual temperature is 28 C, ranging in Bangkok, for example, from 33 C in April to 25C in December. If you're journeying up North, You should be aware that during the cool season, temperatures can get quite chilly at night (as low as 7C), so pack approoriately. In the South the climate is less changeable throughout the year with rain occurring during most months. Check the weather