Due to its favorable geographical location, Thailand has a mild climate, which makes it comfortable to visit year round. In general, the climate is described as tropical, however the region is characterized by its own peculiarities. While the season from late April to mid-November is dominated by summer monsoons, in late November, winter monsoons take hold of the country until February.
High Season
During the high season – from November till February – the weather is mild and comfortable throughout the Kingdom. Even in December, the coldest month of the year, temperatures average around 19 °С, and in the south it is around 26 °С. At night, it never drops lower than 20ºС. The country’s north tends to experience lower temperatures reaching +12 °С or even plummeting to record lows of 0 °С in January. August is considered to be the hottest month in Thailand. In the daytime, the mercury rises to between 30ºС and 34ºС and in the nighttime, temps fall to 25 °С.
Between December and February, the weather is mostly dry with occasional slight rain. The average monthly precipitation varies from 45 to 50 mm. The sea is warm year-round, with surface temperatures exceeding 27 °С.
The north of Thailand is rather cool, especially in the winter (from October to March), so make sure you bring warm clothes. Expect regular precipitation from July until September.
Rainy Season
April normally sees increasing rainfall preceding the monsoon season which starts in May and lasts through October. Torrential rains and thunderstorms are frequent but short and alternate with sunshine. In the daytime, the average temperature falls by 2–3 °С. September and October bear the brunt of the wet weather with the highest daily precipitation amount being 230–250 mm.
The tropical summer lasts from early June till mid-September. In the daytime, it may be as hot as 30ºС to 34ºС. The season between winter and summer (or between summer and winter) is known as ‘inter-season’. This is a time for monsoons, which bring short showers and thunderstorms to Indochina. The average temperature is between 27ºС and 32ºС, so it is never unbearably hot, but pleasantly warm.
Climate of the Islands
In the south (Phuket), two seasons are traditionally distinguished: a relatively mild summer (from November to April and inter-season (from May to October). Though in the inter-season precipitation increases, the weather remains quite comfortable. Usually, it rains once in two days and rainfall doesn’t last longer than two hours. The wettest month is September.
Samui is a perfect holiday destination all year round. However, the best time for visiting the island is considered to be from July to August and from December to February, when daytime temp reaches +30ºС. The inter-season is characterized by short tropical showers, monsoons and sometimes storms (in October and November).