Cambodia Phnom Penh Weather in September — Climate Guide
September in Phnom Penh is moderate
September is moderate for Phnom Penh.
September is monsoon tail with the year's heaviest rainfall at 250mm + 19 rainy days. Days 32°C / 90°F + nights 25°C / 77°F. Pricing remains at June lows — boutique $30-70/night, Raffles + Rosewood + Sofitel $200-450. Pchum Ben (Ancestors' Day, the 15-day Buddhist festival culminating on the autumn full moon — varies year by year, typically late September or early October) is the major cultural event. Cambodians offer food to monks at wats to remember deceased ancestors. The peak day is a public holiday — government and many businesses close, but tourist sites operate normally. Atmosphere is solemn rather than festive — early-morning wat ceremonies (5-6 AM) at Wat Ounalom, Wat Phnom, Wat Botum are the photographic highlight. The trade-off: rain still heavy enough that outdoor photography is compromised. Honestly, September is the hardest sell — only on-property honeymoon couples at luxury hotels and Pchum Ben cultural-photographers consistently report good experiences.
Travel score
Pchum Ben Ancestors' Day + year's lowest pricing + monsoon tail
September Weather at a Glance
September averages 90°F / 32°C highs and 77°F / 25°C lows with 19 rainy days and 250mm of rain — the year's wettest. Humidity 82%. UV 9. Sunshine 6 hours.
September Travel Advice
Travel insurance with cancellation coverage absolutely essential. Plan luxury on-property itinerary + Pchum Ben pre-dawn wat ceremonies (5-6 AM at Wat Ounalom, Wat Phnom, Wat Botum). Korean Chuseok (varies, mid-September) brief regional uptick.
Flying In from Overseas
Year's lowest international flight pricing tied with June. Direct connection via Bangkok $350-650 (year's lowest tied with June). Korean Chuseok holiday brings brief regional uptick.
September Pricing Trends
Year's lowest pricing tied with June: boutique $30-70/night, Raffles $200-450, Rosewood $200-400, Sofitel $170-320. Flights $350-650 via Bangkok / Singapore.
Phnom Penh September Weather Stats
Avg High
32°C
Avg Low
25°C
Rainy Days
19
250mm total
Sunshine
6h
Daily avg
Humidity
82%
very humid
UV Index
9
Very high
Wind
8 km/h
Gusts 22
Sea Temp
29°C
Mekong River muddy + rough
Crowds
Quiet
At attractions
September Sunrise & Sunset
Air Quality
PM2.5
25 μg/m³
PM10
42 μg/m³
Status
good
Feels-Like Temperature & Wind
Feels like
Daytime
37°C
Nighttime
26°C
Humidity and wind affect how the actual temperature feels.
Wind
8 km/h
Max gust 22 km/h
Activities Recommended for September
September Travel Pros & Cons
Pros
- Year's lowest pricing tied with June
- Pchum Ben Buddhist cultural depth
- Tourist crowds at year-low
Cons
- Year's wettest month at 250mm
- Outdoor photography compromised
- Some attractions limited operating hours during Pchum Ben
September Events & Festivals
- Pchum Ben (Ancestors' Day, full moon September) — 15-day Buddhist festival culminating on autumn full moon
- Year's lowest pricing tied with June
- Korean Chuseok holiday imminent
- Western autumn shoulder begins
Phnom Penh in September — Full Picture
September is monsoon tail with the year's heaviest rainfall at 250mm + 19 rainy days. Days 32°C / 90°F + nights 25°C / 77°F. Pricing remains at June lows — boutique $30-70/night, Raffles + Rosewood + Sofitel $200-450. Pchum Ben (Ancestors' Day, the 15-day Buddhist festival culminating on the autumn full moon — varies year by year, typically late September or early October) is the major cultural event. Cambodians offer food to monks at wats to remember deceased ancestors. The peak day is a public holiday — government and many businesses close, but tourist sites operate normally. Atmosphere is solemn rather than festive — early-morning wat ceremonies (5-6 AM) at Wat Ounalom, Wat Phnom, Wat Botum are the photographic highlight. The trade-off: rain still heavy enough that outdoor photography is compromised. Honestly, September is the hardest sell — only on-property honeymoon couples at luxury hotels and Pchum Ben cultural-photographers consistently report good experiences.
What to Wear & What to Pack
Monsoon tail — September is actually one of the wettest months. Rainfall climbs to 250mm. Quick-dry clothes + packable rain shell mandatory. Days 32°C / 90°F + nights 25°C / 77°F.
Packing Checklist
Seasonal Weather Overview
Spring (Mar·Apr·May)
35°C
25°C
7.3/mo
Summer (Jun·Jul·Aug)
32.3°C
25°C
17.7/mo
Autumn (Sep·Oct·Nov)
Current31°C
23.7°C
15/mo
Winter (Dec·Jan·Feb)
31.3°C
22°C
1.7/mo
Phnom Penh Monthly Weather Comparison
| Month | High | Low | Rain | Sun | Humid | UV | Crowd | Price |
|---|---|---|---|---|---|---|---|---|
| January (Best) | 31° | 22° | 1d·10mm | 9h | 65% | 9 | Very busy | Peak |
| February (Best) | 33° | 23° | 1d·10mm | 9.5h | 60% | 10 | Very busy | Peak |
| 35° | 24° | 3d·35mm | 9h | 65% | 11 | Busy | Shoulder | |
| 36° | 26° | 6d·75mm | 8.5h | 70% | 12 | Busy | Peak | |
| 34° | 25° | 13d·145mm | 7.5h | 75% | 11 | Moderate | Shoulder | |
| 33° | 25° | 16d·200mm | 6.5h | 80% | 10 | Quiet | Low season | |
| 32° | 25° | 18d·220mm | 6h | 82% | 10 | Moderate | Shoulder | |
| 32° | 25° | 19d·220mm | 6h | 82% | 10 | Moderate | Shoulder | |
| 32° | 25° | 19d·250mm | 6h | 82% | 9 | Quiet | Low season | |
| 31° | 24° | 17d·240mm | 7h | 80% | 9 | Moderate | Low season | |
| November (Best) | 30° | 22° | 9d·100mm | 8h | 70% | 9 | Very busy | Peak |
| December (Best) | 30° | 21° | 3d·25mm | 9h | 65% | 9 | Busy | Peak |
View Other Months
Phnom Penh September Hotel Picks
Frequently Asked Questions
Is September a good time to visit Phnom Penh?
Phnom Penh in September is moderate. Tourist crowds are quiet and flight/hotel prices are low season.
What's the average temperature in Phnom Penh in September?
Phnom Penh September averages a high of 32°C and a low of 25°C.
Does it rain much in Phnom Penh in September?
Phnom Penh September averages 250mm of rainfall over about 19 rainy days.
What should I wear in Phnom Penh in September?
Monsoon tail — September is actually one of the wettest months. Rainfall climbs to 250mm. Quick-dry clothes + packable rain shell mandatory. Days 32°C / 90°F + nights 25°C / 77°F.
What time are sunrise and sunset in Phnom Penh in September?
Phnom Penh September sunrise is 05:55 and sunset is 17:55, with 12h 00min of daylight.
What's the air quality like in Phnom Penh in September?
Phnom Penh September air quality (AQI) averages 50, rated Good. PM2.5 averages 25μg/m³.
What activities are recommended in Phnom Penh in September?
In September, Phnom Penh is great for Pchum Ben wat ceremonies (pre-dawn), Hotel pool + spa, Cambodian cooking class.
Is September peak season in Phnom Penh?
Phnom Penh September crowds are quiet and prices are low season. You can travel relatively comfortably without long queues.
Best Months to Visit Phnom Penh
View Other Months
Why you can trust weather guide
Based in Chiang Mai for 8+ years, with 30+ countries visited across Southeast Asia, Japan, and Europe. Every detail in this guide is primary-source verified as of April 2026, with prices auto-refreshed via live exchange rate APIs. This isn't AI-generated boilerplate — it's written from the perspective of someone who has actually been there.