Wherever you travel in the world, it is important to get the timing right. Not knowing about a country's seasons and possible weather conditions can turn your holiday into a nightmare. Likewise, gathering some basic details about what to expect will help you make the right decisions about where and when to go.
As far as Thailand is concerned, the best time of year for a visit is between November and February. Generally, the weather is cooler during this period and there is certainly less rain than at other times in the year. However, Thailand is a big country with a diverse landscape. There is somewhere to visit whatever time of the year you visit the kingdom.
Thailand's seasons are reasonably uniform through the country, but there are some regional differences. What follows is a summary of the seasons as they impact the kingdom's various regions:
Central Thailand and the East
In central Thailand and the eastern provinces, the really hot summer weather starts around March and goes on to around November. During this time extreme temperatures can go up to the 45 degrees centigrade mark. The winter months are November to February. There may really be only a few days of genuinely cold weather during these months, but the period leading up to the New Year are a welcome respite from the heat throughout the rest of the year. Aside from these days, visitors from Europe still may feel the temperatures as being a bit warm during Thailand's winter, although not uncomfortably so. The rainy season kicks in around the end of May and goes on until October. The rain is frequent and sometimes fierce. Usually though rainstorms go on for around 30 minutes or so, and after a storm the weather is significantly cooler.
Northern Thailand and the Northeast
Northern Thailand and the Northeast have the same basic seasons as those in the central and eastern regions. The winters are though significantly cooler. Mountainous regions can get particularly cold, on some occasions down to 0 degrees centigrade. In these parts of Thailand's winter starts in November and goes on to January. Without doubt these are the best months for a visit to the North and Northeast - flowers are in bloom, it is dry and cool, and in the mountains mists and fogs often form making what is already wonderful scenery exquisite.
Southern Thailand's seasons are less distinct and really there are only two proper seasons - summer and the rainy season. The Gulf of Thailand lies to the east of the Thai peninsula while the Andaman Sea lies to the west. Visiting areas west of the peninsula (Phuket, Phang Nga, Krabi) is best done between November and April to avoid the monsoons that occur during other months - monsoons obviously make visiting islands by boat difficult and sometimes dangerous. Clearly they are best to be avoided. Areas east of the peninsula (Koh Samui, Hat Yai) are best visited between May and October. If you are planning to visit both sides of the coast during your stay in Thailand, March to April would be the best months.
Thai Government's Meteorological Department
The Thai government's Meteorological Department provides an English language website (http://www.tmd.go.th) with key information about Thailand's weather, including forecasts and summaries. Of particular interest is information on climate and surface temperature - very much worth knowing.