Best time to visit Koh Samui
The best time to visit Koh Samui for a beach holiday is during January and February.
However, anytime during the dry season from mid-December through to early-March is good, with daytime temperatures averaging 28°C (82°F) and little rainfall.
Koh Samui is considered a year-round destination, but it’s probably best to avoid November – the wettest month of the year.
Koh Samui weather
Koh Samui experiences a hot tropical climate with a short dry season from mid-December through April, and rainy season from May to mid-December.
Rain falls throughout the year in Koh Samui, usually in late afternoon or early evening.
What is the best month to visit Koh Samui?
January and February are the best months to visit Koh Samui – the climate is perfect with hot, sunny weather, mostly clear blue skies and little to no rainfall. February is the driest and sunniest month.
However, anytime from mid-December through to early-March is considered good in Koh Samui.
Which is the hottest month in Koh Samui?
May is the hottest month in Koh Samui with an average maximum high of 33°C (91°F), with high heat and humidity, and a night-time low of 28°C (82°F).
The hot season in Koh Samui lasts from April to early-July, with an average daily high temperature above 32°C (89°F).
Which is the coolest month in Koh Samui?
The coldest month of the year in Koh Samui is December, with an average low of 26°C (78°F) and high of 30°C (86°F).
The cool season lasts from November through January, with an average daily high temperature below 30°C (86°F).
When is it sunniest in Koh Samui?
The sunniest time of year in Koh Samui is normally February with nine hours of bright sunshine every day – that's on average 78% of daylight hours.
When is the sea warmest in Koh Samui?
The sea is usually at its warmest in Koh Samui in May when the water temperature reaches 30°C (86°F), which is very pleasant for swimming
The sea in Koh Samui is warm enough to swim year-round.
Which month has the most rain in Koh Samui?
November is the wettest month in Koh Samui with 315mm (12in) of rainfall on average, distributed across 18 days in November.
The wet season typically lasts from May to mid-December, with a greater than 37% chance of a given day being a wet day.
During this time you can expect frequent but brief heavy downpours interspersed with sunny skies. October and November receive the most rainfall.
The drier season lasts from mid-December through April. The month with the fewest wet days in Koh Samui is February.
Which is the windiest month in Koh Samui?
The windiest month of the year in Koh Samui is December, with an average hourly wind speed of 19 kilometres per hour (12 mph; 10 knots).
The windy part of the year lasts from November through January, with average wind speeds of more than 15 kilometres per hour (9 mph; 8 knots).
The less-windy time of year lasts from February through December. The calmest month of the year in Koh Samui is April, with an average hourly wind speed of 12 kilometres per hour (7.5 mph; 6.5 knots).
The predominant average hourly wind direction varies throughout the year in Koh Samui.
October to January also brings strong winds that can make the east side of Koh Samui rough for swimming, while the island's west side is often buffeted by summer monsoons during July and August.
Koh Samui Weather Averages
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
| Average daily max (°C) | |||||||||||
| 30 | 31 | 32 | 32 | 33 | 32 | 32 | 32 | 32 | 31 | 30 | 30 |
| Average daily min (°C) | |||||||||||
| 26 | 26 | 27 | 27 | 28 | 28 | 27 | 27 | 27 | 26 | 26 | 26 |
| Average daily sunshine (hrs) | |||||||||||
| 7 | 9 | 8 | 8 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 |
| Average daily daylight (hrs) | |||||||||||
| 11 | 12 | 12 | 12 | 12 | 12 | 12 | 12 | 12 | 12 | 11 | 11 |
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| Average relative humidity (%) | |||||||||||
| 72 | 71 | 73 | 75 | 80 | 82 | 82 | 82 | 84 | 85 | 81 | 76 |
| UV Index (max) | |||||||||||
| 11 | 11+ | 11+ | 11+ | 11+ | 11+ | 11+ | 11+ | 11+ | 11+ | 11 | 10 |
| Average days of rainfall (≥1mm) | |||||||||||
| 6 | 3 | 4 | 7 | 16 | 15 | 15 | 15 | 17 | 19 | 18 | 11 |
| Average monthly rainfall (mm) | |||||||||||
| 60 | 37 | 57 | 74 | 125 | 124 | 118 | 116 | 146 | 227 | 315 | 174 |
| Average wind speed (km/h) | |||||||||||
| 16 | 15 | 13 | 12 | 13 | 17 | 18 | 19 | 16 | 14 | 18 | 19 |
| Average sea temperature (°C) | |||||||||||
| 28 | 29 | 29 | 30 | 30 | 30 | 30 | 29 | 29 | 29 | 29 | 29 |
| Koh Samui, Thailand | |||||||||||
Holiday seasons
High season: Mid-December to February;
Shoulder season: March to April;
Low season: May to October brings less crowds, cheaper accommodation and, as the locals are quick to point out, it does not rain all day.
Koh Samui weather by month
Note: Meteorological data for Koh Samui is based on weather statistics gathered for the 36-year period 1980 to 2016, and is sourced from the Thai Meteorological Department at the closest weather station, Koh Samui Airport, (USM), located about 2km north of Chaweng. Additional climate data is sourced from the World Meteorological Organization (WMO).
Advice on the best time to visit a particular destination is based on average local weather statistics, when the weather conditions are generally better than at other times of the year. We consider high and low temperatures, risk of rain (and thunderstorms, etc.), amount of sunshine and sea temperature. For general outdoor activities we favour clear, rainless days with a temperature range between 18°C (64°F) and 27°C (80°F); and for hot-weather activities we favour clear, rainless days with a temperature range between 24°C (75°F) and 32°C (89°F). Often, the best times to visit correspond to high season and therefore involve higher prices.
Latest update: Best time6 October, 2023er, 2023
Disclaimer: The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data and conditions at any given location and time are unpredictable and variable. We assume no responsibility and can not be held legally responsible for any decisions made on the basis of the information presented on this site.
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