In northern Thailand the seasons are clearly defined. Between November and May the weather is mostly dry, however this is broken up into the periods November to February and March to May. The latter of these two periods has higher temperatures. The other northern season is from May to November and is dominated by the southwest monsoon, during which time rainfall in the north is at its heaviest. The average high temperature for this region is 32ºC (90ºF) and average low is 21ºC (70ºF), although it can drop down to as low as 8ºC (46ºF) in the winter months.
The central region of Thailand has a hot, tropical climate with daytime temperature reaching the mid-30 ºC (91ºF) throughout the year. November to February is the driest time of year and the most popular with tourists. March, April and May are the hottest months, and the rainy season runs from May to October. During the wet season short showers are likely during the afternoon, though some days it will rain all day.
The southern region of Thailand really has only two seasons - the wet and the dry. These seasons do not run at the same time on the east and west sides of the peninsular. On the west coast the southwest monsoon brings rain from May through to October, whilst on the east coast the most rain falls between September and December. The average high temperature is 33ºC (91ºF) and average low is 25ºC (77ºF).
In general, the best time to visit Thailand is from November to February when the northeast monsoon is blowing cool dry air. During this cool season, the temperature ranges from 18ºC (64ºF) to 32ºC (90ºF) in Bangkok, while in northern and northeast Thailand, temperatures can get quite cool with morning temperatures as low as 8º C (46ºF) to 12º C (54ºF) with the occasional 20ºC (68F) day. Nights can be particularly chilly and at high altitudes the temperatures can and do drop below freezing.
The history of Thailand begins with the migration of the Thais from their ancestral home in southern China into mainland Southeast Asia around the 10th century AD. Prior to this, Mon, Khmer and Malay kingdoms ruled the region. Thais consider the Sukhothai Kingdom, which arose in 1238, to be the first true Thai kingdom and a golden age of peace and prosperity. In 1376 Sukhothai was annexed by the Thai kingdom of Ayutthaya, which defeated the Khmer kingdom of Angkor in 1431. These states fought each other and were under constant threat from the Khmers, Burma and Vietnam. Much later, the European colonial powers threatened in the 19th and early 20th centuries, but Thailand survived as the only Southeast Asian state to avoid colonial rule. After the end of the absolute monarchy in 1932, Thailand endured sixty years of almost permanent military rule before the establishment of the current democratic system.