What is the weather like in Siem Reap in September?

Expect temperatures between 25°C and 30°C with 79% average rain probability and about 8 hours of sunshine daily.

What is the weather like in Siem Reap in September?

Siem Reap in September scores 52/100 based on 30 years of climate data. A reasonable choice for your trip.

Who should visit Siem Reap in September?

September in Siem Reap is ideal for: Business travelers.

Siem Reap Weather in September | 30-Year Forecast

Avg High

30°C

Hottest around day 1

Avg Low

25°C

Coolest around day 22

Rainy Days

30days

79% avg rain chance

Sunshine

8hrs/day

Autumn season

Essential Travel Info for Siem Reap

🗓️ Best Time to Visit 📖 Travel Guide 🍴 Food Guide

Currency

KHR

៛ Cambodian riel

Language

Khmer

Driving

Right side

Connect

Wifi is available in all the usual place...

Safety

High Safety

GPI: 1.882

Travel Intelligence

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Health & Safety Advisory

CDC travel health recommendations

10 Recommendations

COVID-19

All eligible travelers should be up to date with their COVID-19 vaccines. Please seeYour COVID-19 Vaccinationfor more information.

Chikungunya

All travelers should take steps to prevent mosquito bites. Chikungunya vaccination is generally not recommended. Travelers who wish to consider vaccination can visit “What to consider before traveling” on thechikungunya vaccinespage to learn more.

Hepatitis A

Recommended for unvaccinated travelers one year old or older going to Cambodia.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 Cambodia. Unvaccinated travelers 60 years and older may get vaccinated before traveling to Cambodia.

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.

Malaria

CDC recommends that travelers going to certain areas of Cambodia take prescription medicine to prevent malaria. Depending on the medicine you take, you will need to start taking this medicine multiple days before your trip, as well as during and after your trip. Talk to your doctor about which malaria medication you should take.Transmission areasPrimarily isolated to pockets in rural and forested areasRare cases in non-forested areasNo (or negligible) malaria transmission in the cities of Phnom Penh (the capital) and Siem ReapNo (or negligible) malaria transmission at the main temple complex at Angkor WatDrug resistanceChloroquine and mefloquineSpeciesP. vivax(95%)P. falciparum(5%)P. malariaeandP. knowlesi6(rare)Recommended chemoprophylaxisRural and forested areas: Atovaquone-proguanil, doxycycline, primaquine5, tafenoquine2Areas with rare cases: No chemoprophylaxis recommended (insect bite precautions and mosquito avoidance only)4Updated April 23, 2025See footnotes

+4 more

Source: CDC Travelers' Health

View Complete Health Guide

Is September a Good Time to Visit Siem Reap?

👌A reasonable choice for your trip(52/100)

Short Answer

Siem Reap in September tests even seasoned travelers: 31°C daytime temperatures and 86% humidity mean early mornings or evenings are your best windows for sightseeing.

Decision Factors

Oppressive heat and humidity

30.5°C with 86% humidity - challenging conditions

High rainfall period

79% rain probability, 7.9mm average

Vaccinations required

Yellow Fever

Feels significantly hotter than 30.5°C

Heat index: 41°C due to 86% humidity

Health precautions needed

Be aware of: Leptospirosis, Melioidosis, Schistosomiasis

Shoulder season - balanced conditions

50% of peak - good value with moderate crowds

Good For

💼
Business travelers
Climate-controlled meetings unaffected by weather

Who Should Avoid

👨‍👩‍👧‍👦
Families with children
41°C heat index dangerous for children
👴
Elderly travelers
Heat index of 41°C poses health risks
🥾
Outdoor enthusiasts
79% rain probability disrupts outdoor activities
📸
Photographers
90% cloud cover limits natural light opportunities

"According to 30YearWeather's analysis of 30 years of NASA POWER satellite data,Siem Reap in September averages 30°C with 79% precipitation probability."

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

Frequently Asked Questions: Siem Reap in September

What are the temperatures in Siem Reap in September?

Daytime highs average 30°C, nights drop to 25°C. Temperatures remain fairly consistent.

How many rainy days in Siem Reap in September?

Expect around 30 days with measurable rainfall. Definitely pack rain gear.

What to wear in Siem Reap in September?

Light, breathable fabrics. Don't forget sunglasses and a hat.

Is September peak season in Siem Reap?

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

Siem Reap Weather in September

Siem Reap September Weather Calendar