Thailand is a tropical country with a climate to match, but in general is not oppressively hot or humid as in some other tropical countries. How comfortable a visitor will feel when first arriving depends chiefly on where they come from originally; for example, visitors arriving from mid winter in northern Finland, where temperatures can be minus 30 °C, will experience an approximate 60-70 degree temperature difference on arriving in Thailand. However, people acclimatise pretty quickly.
The Thais have a lovely humorous way of describing their three seasons: hot, hotter and hottest seasons! But in general, when talking about Thailand’s climate, guidebooks and websites will tell you that the 3 seasons are the “cool” season from November to February, the “hot” season from March to June, and the “rainy” season from July to October. Few of these resources will tell you however that this pattern is true for only one part of Thailand: Bangkok & the Central Plains, the North and the North East. The Southern part of Thailand that stretches down to Malaysia has just two seasons (hot or rainy) with weather more susceptible to the monsoons and which varies between the two sides of the Peninsula. In contrast, during the middle of the year, the far Eastern Coast and islands close to Cambodia, become the wettest place in the country.
The Cool Season (November to February): the nicest most comfortable period for travelling to Thailand with cool sunny days. Temperatures are between 30 and 35°C, with humidity from 50%to 60%. Temperatures in the North are likely to be even cooler which may necessitate a pullover or cardigan in the evening. Morning fog over a lake or river may greet visitors to the North at breakfast time, but this will get burnt off as the sun rises. Thailand’s high season corresponds with these ideal weather conditions: prices are at their highest, demand is greatest, and availability can be difficult to obtain.
The Hot Season (March to June): finds Thailand at its hottest (temperatures can be as high as 40°C) and its most humid. The water throwing festival of the Thai New Year or Songkran can provide much welcome relief from the heat. As the season progresses, rain becomes more apparent mostly falling as evening or nighttime showers. Songkran marks the end of the tourist high season, and from April till October you will find the cheapest accommodation rates.
The Rainy Season (July to October): sees Thailand at its greenest and freshest. Despite the off-putting term “rainy” to those in search of sunshine, the rain generally comes in the late afternoon or evening and rarely lasts more than an hour. The showers are the characteristic tropical torrential downpour, with some thunderstorms, not the drizzles associated with more northern climes. With the rains come cooler temperatures. Flooding can occur in September and October with the rains at their peak, and the rivers at their highest. At this time of year, you can come and enjoy Thailand at its cheapest and at a less crowded pace. This is the peak period for visitors from the Middle East who delight in the cooler fresher climate and who enjoy seeing some rain and greenery!
The driest beach resorts year round are those closest to Bangkok: Pattaya and Cha Am + Hua Hin, and that gorgeous paradise island of Ko Samet, just a little further away in Rayong province.
Southern Thailand is always hot and humid with two seasons: the Hot and Monsoon seasons.
The fiercest monsoon months in the South West (including Phuket and Krabi) are May, September & October.
In the South East (including Samui & nearby islands) the monsoon is at its fiercest from October to December.
The best time to visit these beach resorts which border the Andaman Sea at the Indian Ocean’s most eastern extremity, is from November to April when the winds come from the North East, bringing with them cool, dry air and sunshine, but March and April can feel more humid.
From May to October, the winds bring warm moist air with rain from the South West over the Indian Ocean, and the three wettest monsoon months in this region are in May, September and October. However, June to August is still a very pleasant period to visit, with attractive low season prices and not too much rain. Antipodean visitors love Phuket and Krabi at this time during the Southern Hemisphere’s winter months.
Further north up the coast on the mainland, the ever increasingly popular destination of Khao Lak sits at the edge of the rain forest where it meets the sea. Khao Lak can be wetter during the rainy season, or as the hoteliers there like to say ‘greener’! Travelling to and from the islands in the Andaman Sea can be more challenging with less frequent ferries and higher seas.
The climate of these islands, located on the Gulf of Thailand side of the Peninsula, differs considerably from the other side where Phuket and Krabi are located. The monsoon period here is October to mid December, and these islands can have some fierce storms at that time. However, being more centrally located in the Gulf, Ko Tao has slightly better and drier weather. The coolest and driest time to visit Samui and these islands is in January and February; there’s plenty of sunshine with pleasant temperatures. It heats up from March to May, but the islands generally remain dry with nice calm seas. The rains start in June with late afternoon thunderstorms but with plenty of daytime sunshine. Despite the attractive pricing available from October to December, it can be a miserable experience to be on the islands in the middle of the monsoon, especially when so many other beach resorts in the country are bright warm and sunny!
The weather here closely follows that if the central plains. However, as you can see on the climate chart, the official records from the Thai Meteorological office show this area has by far the highest rainfall in the entire kingdom! To be honest, these figures seem very high, but these figures are worth bearing in mind when choosing your holiday destination!