What is the weather like in Koh Samui in September?

Expect temperatures between 23°C and 27°C with 50% average rain probability and about 8 hours of sunshine daily.

What is the weather like in Koh Samui in September?

Koh Samui in September scores 60/100 based on 30 years of climate data. Good option with minor considerations.

Who should visit Koh Samui in September?

September in Koh Samui is ideal for: Cultural tourists, Business travelers.

Koh Samui Weather in September | 30-Year Forecast

Avg High

27°C

Hottest around day 1

Avg Low

23°C

Coolest around day 27

Rainy Days

30days

50% avg rain chance

Sunshine

8hrs/day

Autumn season

Sea Temperature in September

Coastal Waters(Ocean)

30.1°C

Monthly Average

Water Feel

🌴Tropical

Perfect for swimming and water sports

Swim Rating

✅Excellent for swimming

Based on average sea surface temperature

Body of Water

Coastal Waters

Ocean

Koh Samui coastline

Essential Travel Info for Koh Samui

🗓️ Best Time to Visit 📖 Travel Guide 🍴 Food Guide

Currency

THB

฿ Thai baht

Language

Thai

Driving

Left side

Safety

Moderate Safety

GPI: 2.098

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

Low Traffic

21/ 100

Traffic Index

Quieter airport

Peak Daily Arrivals

slots per day

Peak

Feb

Low

Jun

Monthly Traffic Distribution

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Traffic Level

Low Season

Key Connections

Bangkok Suvarnabhumi (BKK)

Singapore Changi (SIN)

Chiangmai Chiang Mai (CNX)

Hong Kong Chek Lap Kok (HKG)

Health & Safety Advisory

CDC travel health recommendations

11 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There is no longer active cholera transmission and vaccine is not recommended.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 Guide

Is September a Good Time to Visit Koh Samui?

👌Good option with minor considerations(60/100)

Short Answer

Storm season alert for Koh Samui in September: beyond the 27°C, 50% rain averages, hurricane risk requires travel insurance and schedule flexibility.

Decision Factors

Typhoon season active

Western Pacific zone - expect potential typhoon activity

Vaccinations required

Yellow Fever

Warm tropical seas

30.1°C sea temperature - Hot Soup

Frequent rainfall expected

50% chance of rain - pack waterproofs

Health precautions needed

Be aware of: Leptospirosis, Melioidosis, Dengue

Plenty of sunshine

8.8h of sunshine daily

Good For

🏛️
Cultural tourists
Comfortable conditions for exploring museums and sites
💼
Business travelers
Climate-controlled meetings unaffected by weather

Who Should Avoid

👴
Elderly travelers
79% humidity creates difficult conditions
📸
Photographers
88% cloud cover limits natural light opportunities
💼
Business travelers
Storm season may cause flight disruptions

"According to 30YearWeather's analysis of 30 years of NASA POWER satellite data,Koh Samui in September averages 27°C with 50% precipitation probability."

📊 Source: 30YearWeather.com🛰️ Data: NASA POWER (1991-2021)View Methodology →

Frequently Asked Questions: Koh Samui in September

What are the temperatures in Koh Samui in September?

Daytime highs average 27°C, nights drop to 23°C. Temperatures remain fairly consistent.

How many rainy days in Koh Samui in September?

Expect around 30 days with measurable rainfall. An umbrella is advisable.

What to wear in Koh Samui in September?

Comfortable casual wear with a light jacket for evenings.

Is September peak season in Koh Samui?

This is off-peak season. Expect lower prices and fewer crowds.

Koh Samui Weather in September