There are two important aspects to take into account: the first being the weather, and the second being the difference between the ‘high’ season and the ‘low’ season. This determines how busy the golf courses are.
Thailand has a tropical climate featuring three distinct seasons. In most areas, the hot season extends from March to May; the green season from June to October and the cool season from November to February.
It is mild and sunny during the cool season with humidity being considerably lower than other times of the year. Average temperatures during this time of the year range between 35.5° Centigrade (96° Fahrenheit) to 16° Centigrade (62° Fahrenheit) with clear skies and light breezes. This provides great golfing conditions. The cool season is the peak tourist season and accommodation and the golf courses can be busy, especially in the more populated areas.
During the hot season, which begins in April, day-time temperatures can reach 40° Centigrade (104°Fahrenheit). However the increase in temperature is quite gradual so conditions remain quite pleasant. At the peak of the season, hot dry weather prevails throughout Thailand.
The best time to play golf during should be early in the morning, or after lunchtime, hence avoiding the hottest part of the day.
Most rain falls during the green season from June to September. While intermittent showers or thunderstorms occur at various times of the day, it is perhaps the driest rainy period of any country in Southeast Asia with plenty of sunshine. It is possible to golf practically everyday as rain showers tend to be brief and courses dry quickly.