Climate Thailand
Due to its latitude and the influence of the southwest and northeast monsoons, Thailand enjoys a humid tropical climate throughout the year. The distance from north to southeast is around 1,900 km, and the latitude gradient is around 15°, with Mae Sai in the north at 20.5°N and Betong in the south at 5.6°N. Together, these factors give Thailand one of the most varied climates in Southeast Asia. The northeast monsoon (November-December to February-March) brings cool, dry air, while the southwest monsoon (May-June to October-November) brings its share of rain (monsoons determine rainfall, which in turn determines the seasons). Since the onset of deforestation in Southeast Asia over the last 25 years, the climate has changed dramatically, becoming extremely unpredictable. It sometimes rains in the dry season, and in winter, when it should be below 20°C in Chiang Mai, the temperature can rise to 28°C.
The seasons
There are two seasons in Thailand, with differences in thermal gradient between regions: the dry season from November to April, and the rainy season from May to October. Some say three seasons, the third being a sub-section of the dry season, especially pronounced in the north. The monsoon season peaks in July, August and September. Throughout the country, March and April are the hottest months.
Bangkok
I might as well warn you: Bangkok is hot all year round! Minimum temperatures fluctuate between 21° and 26°C, maximum temperatures between 31° and 37°C. The best time to visit the city is from November to February, when it's hot but not too humid, and the skies are clear, although there may be sporadic rain. From March to May, it's very hot and the humidity is quite high. The monsoon arrives around the end of May, and lasts until October. Temperatures drop, but humidity rises, rains are relatively frequent and thunderstorms can occur. Skies are often grey and cloudy, but there are occasional clear spells between showers. Occasionally, streets are completely flooded.
The North
The northern plains are also warm all year round, although nights can be cool in winter. Minimum temperatures range from 14° to 24°C, while maximum temperatures range from 28° to 36°C. In Chiang Mai, night-time temperatures can fall to 5°C in December and January, but between March and May they can reach 38°C during the day! The best time to visit Northern Thailand is from December to mid-February.
In the mountainous northern regions bordering Myanmar and Laos, the climate varies according to altitude. Nights can be cold in winter, but days are pleasant with clear skies. Monsoon rains are heavier here than on the plains.
The South East
The area along the Gulf of Siam, from Prachuap Khiri Khan to the Malaysian border (including the islands of Koh Samui, Koh Phangan, and Koh Tao), is known as the rainy coast. The heat is constant and temperatures vary little. Water temperatures fluctuate between 26° and 30°C all year round. Ideal for swimming! The monsoon season is less intense (May to September), with regular light showers. On the other hand, from October to November, this area experiences a reverse monsoon, favored by the warmth of the sea. Rains are abundant and frequent.
The South West
The climate along the Andaman coast is different from that along the Gulf of Thailand. This area includes the most famous seaside resorts: Phuket, Krabi, Khao Lak, Phang Nga Bay, and the islands of Koh Lanta, Koh Phi Phi and Koh Lipe. Torrential rains fall in summer during the monsoon season, with an intense period around September and October. Sea transport can be affected by the rough seas. The best time to visit is from December to March.
Cyclones and tsunamis
Cyclones frequently sweep across southern Thailand (from Bangkok to the Malaysian border), but their intensity varies greatly. Cyclones from the Pacific are called typhoons and move from east to west. They are frequent from September to November. Cyclones from the Indian Ocean, on the other hand, move from west to east, and can affect the southern part of the country all year round, but more particularly between May and December. Typhoons and cyclones can bring violent winds and torrential rain.
On December 26, 2004, Thailand was hit hard by the worst tsunami in history. It mainly affected the western part of the country (Andaman Sea coast), killing 5,395 people, leaving 2,845 missing and injuring 8,450 (according to official sources), the majority of whom were foreign tourists. The tsunami was triggered by an earthquake in the Indian Ocean, the epicenter of which was near the island of Sumatra (Indonesia). The damage was titanic. The government's lack of prevention led to the creation of a tsunami warning system. The National Disaster Warning Centre can alert the population, via satellites and warning towers, within 15 minutes of the first wave forming. Evacuation plans for high-risk areas are also in place. You're sure to spot these warning towers and evacuation signs during your stay on the country's southwest coast.
