Thailand's climate is tropical, and is largely affected by the North-East Monsoon and the South-West Monsoon, which bring changes in weather patterns on a cyclical basis. The central, northern and north eastern areas have three seasons which are: Cool dry season from November to February; Hot dry season from March to June and Wet season from July to October.
The Southern peninsula areas and the deep south of Thailand, are subject mainly to two seasons based on the monsoons. The Eastern side of the peninsula (Koh Samui side) will receive its best conditions from May to November, while the Western side (Phuket side) receives it's ideal conditions between November and April.
Throughout the year in Thailand, though there is always sunshine, however the amount of sunshine will vary depending on the time of year. For example, September is the month, which receives the most rainfall in much of Thailand and also has the lowest hours of sunshine per day.
