Peak in July
Coolest in December
Heavy in October
Peak in dry season
Sea Temperature
Coastal Waters(Ocean)
Annual Average
Perfect for swimming and water sports
Based on average sea surface temperature
Ocean
Koh Samui coastline
Koh Samui Monthly Weather Guide
Click any month to explore daily weather forecasts
January
February
March
April
May
June
July
August
September
October
November
December
Essential Travel Info for Koh Samui
Currency
THB
฿ Thai baht
Language
Thai
Driving
Left side
Safety
Moderate Safety
GPI: 2.098
Best Time to Visit Koh Samui
Location, climate overview & historical trends
Tap to Explore Map
📍 9.5120° N, 100.0136° E
Open in Google MapsKoh Samui is a prominent destination in Thailand.
Located at 9.51°N latitude,Koh Samui experiences a tropical climate with warm temperatures year-round.
Based on 30 years of data, July is the warmest month (avg. 28°C), while December is the coolest. October sees the most rain (67% chance), making February the driest month.
Historical Climate Trend
30-Year Analysis+1.88°C
Total over 30 years
+0.63°C
Per decade
Linear regression analysis of historical maximum temperatures for Koh Samui, based on 1995-2024 satellite data from NASA POWER.
Best Time to Visit
NASA POWER Data (1991-2021)January, February, March
Best months to visit
27°C
Avg High
Based on 30 years of NASA satellite data,Koh Samui receives approximately 1,098mm of rainfall annually. These months offer optimal temperatures and minimal rain probability for your visit.
Climate Trends
EXCLUSIVE1995-2040 Temperature Trend
1995 Avg
25.9°
2024 Avg
27.4°
2040 Proj
27.7°
+0.63°C
per decade (observed)
+0.21°C
per decade (CMIP6)
🌡️ Koh Samui has warmed by +1.9°C since 1995. By 2040, an additional +0.3°C is projected (based on CMIP6 rate of 0.211°C/decade), for a total of +2.2°C from 1995 baseline.
NASA POWER (1995-2024) + CMIP6 (CMCC_CM2_VHR4, EC_Earth3P_HR, FGOALS_f3_H, HiRAM_SIT_HR, MRI_AGCM3_2_S, NICAM16_8S)
Travel Intelligence
Exclusive flight analytics & health data for Koh Samui
Smart Flight Estimator
Airport-to-Airport Logistics
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Flight Connectivity Analysis
Airport traffic data & seasonal patterns
Quieter airport
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slots per day
Peak
Feb
Low
Jun
Monthly Traffic Distribution
Key Connections
Health & Safety Advisory
CDC travel health recommendations
COVID-19
All eligible travelers should be up to date with their COVID-19 vaccines. Please seeYour COVID-19 Vaccinationfor more information.
Chikungunya
There iselevated chikungunya riskin Thailand.Chikungunya vaccinationmay be considered for people traveling or moving to this location if they are planning to stay for an extended period of time (for example, 6 months or more).
Cholera
There is no longer active cholera transmission and vaccine is not recommended.
Hepatitis A
Recommended for unvaccinated travelers one year old or older going to Thailand.Infants 6 to 11 months old should also be vaccinated against Hepatitis A. The dose does not count toward the routine 2-dose series.Travelers allergic to a vaccine component should receive a single dose of immune globulin, which provides effective protection for up to 2 months depending on dosage given.Unvaccinated travelers who are over 40 years old, are immunocompromised, or have chronic medical conditions planning to depart to a risk area in less than 2 weeks should get the initial dose of vaccine and at the same appointment receive immune globulin.
Hepatitis B
Recommended for unvaccinated travelers younger than 60 years old traveling to Thailand. Unvaccinated travelers 60 years and older may get vaccinated before traveling to Thailand.
Japanese Encephalitis
Recommended for travelers whoAre moving to an area with Japanese encephalitis to liveSpend long periods of time, such as a month or more, in areas with Japanese encephalitisFrequently travel to areas with Japanese encephalitisConsider vaccination for travelersSpending less than a month in areas with Japanese encephalitis but will be doing activities that increase risk of infection, such as visiting rural areas, hiking or camping, or staying in places without air conditioning, screens, or bed netsGoing to areas with Japanese encephalitis who are uncertain of their activities or how long they will be thereNot recommended for travelers planning short-term travel to urban areas or travel to areas with no clear Japanese encephalitis season.
+5 more
Source: CDC Travelers' Health
View Complete Health GuideKoh Samui Climate Data by Month
Historical temperature and precipitation averages
| Month | Avg High (°C) | Rain Probability (%) | Status |
|---|---|---|---|
| January | 25°C | 22% | ✨ Perfect |
| February | 26°C | 16% | ✨ Perfect |
| March | 27°C | 17% | ✨ Perfect |
| April | 28°C | 27% | 😊 Pleasant |
| May | 28°C | 41% | 🌧️ Rainy |
| June | 28°C | 36% | Neutral |
| July | 28°C | 36% | Neutral |
| August | 27°C | 35% | Neutral |
| September | 27°C | 50% | 🌧️ Rainy |
| October | 26°C | 67% | 🌧️ Rainy |
| November | 25°C | 63% | 🌧️ Rainy |
| December | 25°C | 36% | Neutral |
Weather in Cities Near Koh Samui
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Compare weather conditions with nearby destinations for your trip planning
Compare Koh Samui Weather vs Popular Destinations
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These destinations share similar weather patterns with Koh Samui. Perfect alternatives if you're looking for the same climate in a different location.
Koh Samui Weather FAQ
When is the best time to visit Koh Samui?
Honestly, look for months with mild temperatures (20°C-25°C) and low rain chance. Based on historical data, January, February, March are usually great choices.
When is the hottest month in Koh Samui?
July is historically the hottest month in Koh Samui with average highs of 28°C.
When does it rain the most in Koh Samui?
October typically sees the highest probability of rain (67%).
Is Koh Samui expensive?
Prices vary by season. The "Perfect" weather months usually coincide with peak tourist season and higher prices, while the rainy or cold months offer better deals.