The best times to visit Koh Samui for ideal weather are
January 29th to March 25th
based on average temperature and humidity from NOAA (the National Oceanic and Atmospheric Administration). Read below for more weather and travel details.
Koh Samui Travel Guide
Weather in Koh Samui
Average temperatures in Koh Samui vary very little. Considering humidity, temperatures feel hot all year with a chance of rain throughout most of the year. The area is far less temperate than some — in the 4th percentile for pleasant weather — compared to tourist destinations worldwide. Weeks with ideal weather are listed above. If you’re looking for the very warmest time to visit Koh Samui, the hottest months are May, June, and then April. See average monthly temperatures below. The warmest time of year is generally mid April where highs are regularly around 92.2°F (33.4°C) with temperatures rarely dropping below 78.2°F (25.7°C) at night.
Koh Samui Temperatures (Fahrenheit)
Koh Samui Temperatures (Celsius)
The way we experience weather isn’t all about temperature. Higher temperatures affect us much more at higher humidity, and colder temperatures feel piercing with high winds. Our perceived temperatures factor in humidity and wind chill to better represent how hot or cold the day feels to a person.
Koh Samui Perceived Temperature (F)
Koh Samui Perceived Temperature (C)
Average Koh Samui Temperatures by Month
Daily highs (averaged for the month) usually give the best indication of the weather. A significantly lower mean and low generally just means it gets colder at night.
|Month||Avg. High (°F)||Avg. Mean (°F)||Avg. Low (°F)|
|Month||Avg. High (°C)||Avg. Mean (°C)||Avg. Low (°C)|
Precipitation (Rain or Snow)
If dry weather is what you’re after, the months with the lowest chance of significant precipitation in Koh Samui are February, March, and then April. Note that we define “significant precipitation” as .1 inches or more in this section. The lowest chance of rain or snow occurs around early February. For example, on the week of February 5th there are no days of precipitation on average. By contrast, it’s most likely to rain or snow in late October with an average of 4 days of significant precipitation the week of October 22nd.
When can you find snow in Koh Samui? Weather stations report no annual snow. Please note that a value of 0 for snow in the graph below may either mean there was no snow, or that snow is unreported.
The graph below shows the % chance of rainy and snowy days in Koh Samui.
Snow on the Ground
The graph below shows the average snow on the ground in Koh Samui (in).
Average Rain and Snow by Month
|Month||Daily Chance of Rain||Average Snow Depth (in)||Total Precipitation (in)|
|Month||Daily Chance of Rain||Average Snow Depth (cm)||Total Precipitation (cm)|
Humidity and Wind
Koh Samui has some extremely humid months, and high humidity throughout the year. The least humid month is June (71.7% relative humidity), and the most humid month is November (81.5%).
Wind in Koh Samui is usually extremely calm. The windiest month is February, followed by January and March. February’s average wind speed of around 4.9 knots (5.6 MPH or 9 KPH) is considered “a light breeze.” Maximum sustained winds (the highest speed for the day lasting more than a few moments) are at their highest in late January and early February where average top sustained speeds reach 9.4 knots, which is considered a gentle breeze.
Relative Humidity (%)
The graph below shows the average % humidity by month in Koh Samui.
The graph below shows wind speed (max and average) in knots.
Average Wind Speeds
Show Wind Speeds
All wind speeds are in knots. 1 knot = 1.15 MPH or 1.85 KPH.
|Month||Avg. Wind||Avg. Wind Feel||Sustained High Wind||High Wind Feel|
|Jan||4.2||Light breeze||8.1||Gentle breeze|
|Feb||4.9||Light breeze||8.1||Gentle breeze|
|Mar||3.8||Barely noticeable||7.4||Gentle breeze|
|Apr||2.2||Barely noticeable||6.2||Light breeze|
|May||1.5||Barely noticeable||5.8||Gentle breeze|
|Jun||1.7||Barely noticeable||5.9||Light breeze|
|Jul||1.6||Barely noticeable||5.9||Gentle breeze|
|Aug||2||Barely noticeable||6.4||Light breeze|
|Sep||2||Barely noticeable||6.2||Gentle breeze|
|Oct||1.9||Barely noticeable||6.3||Light breeze|
|Nov||3||Barely noticeable||7.7||Gentle breeze|
|Dec||3.7||Barely noticeable||7.8||Gentle breeze|
Show Relative Humidity by Month
|Month||Avg. Relative Humidity|
Is it Safe to Travel to Koh Samui?
Our best data indicates this area is somewhat safe, but with extra warnings in a few regions. As of Nov 23, 2018 there are travel warnings and regional advisories for Thailand; exercise a high degree of caution and avoid some areas. Check this page for any recent changes or regions to avoid: Travel Advice and Advisories
The Busiest and Least Crowded Months
The busiest month for tourism in Koh Samui, Thailand is January, followed by August and July. Prices for hotels and flights will be most expensive during these months, though you can save if you purchase well in advance. Tourists are unlikely to visit Koh Samui in May. Those willing to visit at these times will likely find it the least expensive month.
Estimated Tourism by Month
Most Popular Months to Visit
Overall Koh Samui Travel Experience by Season
Spring (March through May)
Humidity and temperatures combine to make this season feel warm. Highs range from 92.2°F (33.4°C) and 85.8°F (29.9°C) with similar temperatures in the later months. Rain is somewhat common with 5 to 10 days of significant precipitation per month. Spring is the slowest for tourism, which makes it a good time for those looking for deals.
Summer (June through August)
The middle-year months have very comfortable weather with high temperatures that are quite warm. These months see moderate precipitation with 7 to 10 days of precipitation per month. June – August is the second busiest season for tourism in Koh Samui, so lodging and other accommodations may cost slightly more.
Fall (September through November)
Fall daily highs range from 89.9°F (32.2°C) and 85.2°F (29.6°C), which will feel very nice given the humidity and wind. It rains or snows a great amount: 8 to 16 days per month. Tourism is fairly slow during these months due to the weather, so hotels may be lower priced.
Winter (December through February)
Weather is perfect this time of year in Koh Samui to be enjoyable for warm weather travelers. The average high during this season is between 85.8°F (29.9°C) and 83.9°F (28.8°C). On average, it rains or snows a fair amount: 3 to 10 times per month. These times of year are the busiest with tourists.