Weather in Koh Samui

Stay updated on the latest weather conditions in Koh Samui. Below you will find current data, forecasts, and useful weather charts to ensure your stay is as comfortable as possible.

Koh Samui, located in Thailand, boasts a typical tropical monsoon climate. This means it is warm and sunny for most of the year, with temperatures that fluctuate very little. The average annual temperature stays within a comfortable range of 26°C to 29°C, making the island an attractive destination to visit at any time.

Two main seasons can be distinguished on the island. The dry season usually lasts from January to April, characterized by minimal rainfall and a large number of sunny days. During this period, the average air temperature is around 26-28°C. From May to December, the rainy season sets in, although the intensity of rainfall varies. The highest number of rainy days and amount of precipitation occurs in October and November, when up to 11 mm of precipitation falls and there are up to 28 rainy days per month. However, even during the rainy season, showers are often short and refreshing, and the sun returns quickly.

Despite the presence of a rainy season, temperatures on Koh Samui remain high and stable year-round, making it a popular destination for beach lovers. Tourists should note that from May to August there is also an increase in the number of days with precipitation, although the total amount is less than during the peak of the rainy season in autumn.

The climate on Koh Samui is distinguished by consistently warm weather throughout the year, making it attractive for tourists in any season. Average annual temperatures fluctuate within a fairly narrow range, typically from 26.6°C to 28.7°C. The hottest months are usually April and May, when the average temperature reaches 28.5°C - 28.7°C, and daily highs can rise to nearly 29.8°C. The so-called "cool" season falls in December and January, with average temperatures around 26.6°C, yet the weather on the island remains very warm even during this time.

On Koh Samui, there are no sharp contrasts between "summer" and "winter" as in temperate latitudes; rather, one can speak of a hotter season and a slightly less hot one. During the peak heat period, roughly from March to June, daytime temperatures are consistently high, with average maximum values often hovering around 29-30°C. Even in the so-called "cool" season, from November to February, the island is very warm, and average minimum temperatures rarely drop below 25.8°C. A characteristic feature of the climate of Koh Samui is the insignificant difference between day and night temperatures. Daily fluctuations usually amount to just 1.5-2.5°C, which means nights remain almost as warm as the days.

The temperature regime on Koh Samui is characterized by constant tropical heat. Throughout the year, both average minimum and average maximum temperatures confidently stay above the 25°C mark. For example, even in January, the "coolest" month, the average minimum is 25.8°C, and the average maximum is 27.4°C. In the hottest month, May, these figures rise to an average minimum of 27.5°C and an average maximum of 29.8°C. Such stable heat, often accompanied by high humidity (especially in the rainy months), creates a classic tropical island atmosphere, ideal for a beach holiday at any time of the year for those who love warmth.

The climate on the island of Koh Samui is characterized by a distinct division into dry and wet seasons, which directly affects the amount and frequency of precipitation throughout the year. Snow does not fall here; all precipitation comes in the form of rain, typical for a tropical climate.

The driest period on Koh Samui is usually observed from January to April. March stands out particularly as the driest month: on average, only about 1 mm of precipitation falls, and the number of rainy days is minimal – about 7. January and February are also relatively dry, with precipitation amounts of about 2 mm and 9-11 rainy days respectively. April marks the transition to a wetter period, with an increase in precipitation to 4 mm and approximately 13 rainy days.

The rainy season on the island gathers strength from May and reaches its peak in autumn. The wettest months are considered to be October and November. In October, despite the total precipitation being about 8 mm, it rains very frequently – on average 28 days in the month. November leads in the amount of precipitation (about 11 mm) with 24 rainy days. The period from May to August is also characterized by a significant number of rainy days (20-22 days per month), although the total amount of precipitation in these months is somewhat lower (3-4 mm), which may indicate frequent but perhaps less intense tropical showers. December also remains quite wet, with 7 mm of precipitation and approximately 16 rainy days, concluding the main wet season.

When planning a trip to Koh Samui, consider that a typical tropical climate with high temperatures throughout the year awaits you. The average annual temperature fluctuates between 26-29°C, so the basis of your luggage should be light, breathable clothing made from natural fabrics such as cotton and linen. Be sure to pack swimwear, shorts, t-shirts, and sundresses. Do not forget about reliable sun protection: high SPF sunscreen, quality sunglasses, and headwear (a hat or cap) will help avoid sunburn and heatstroke. For walks and excursions, you will need comfortable open shoes, such as sandals or flip-flops, as well as light sneakers or loafers for longer hikes.

Although it is warm year-round on Koh Samui, it is worth paying attention to the seasonality of rainfall. The greatest amount of rain falls in the period from September to November (6-11 mm of precipitation, up to 28 rainy days in October). If your trip falls during these months or the period from May to August, when frequent albeit less intense rains are also possible, be sure to pack a light waterproof raincoat or a compact umbrella. Clothing made from quick-drying materials will also be very useful. In the drier months, from January to March, when the amount of precipitation is minimal (1-2 mm), the likelihood of catching a heavy downpour is lower, but a small folding umbrella may still come in handy. Regardless of the season, you will not need heavy and overly warm clothing.

Besides clothing, do not forget to bring insect repellent, especially if you plan evening walks or visits to nature parks. A small first aid kit with basic medications may also be useful. Given the hot climate, it is important to drink enough water, so a reusable water bottle will be a helpful accessory. A light scarf or pareo can serve several functions: protecting your shoulders from the sun, covering them when visiting temples, or providing a little warmth in air-conditioned rooms.