Fall in Phnom Penh really changes things up from the heavy rains of summer. You’ll notice drier, clearer skies moving in.
Most days stay warm, hovering around 88°F (31°C), and nights rarely dip below 77°F (25°C). It’s still hot, but at least it’s not as wet as before.
This mix of steady warmth and less rain makes fall one of the more comfortable times to be in Cambodia’s capital.
As September slides into November, clouds thin out and rain becomes much less common. Early fall still brings plenty of showers, but by late November, you’ll see a lot more sun and far fewer downpours.
Humidity drops a bit too, though the air usually feels muggy. That’s just the tropics for you.
These slow changes shape daily life and travel. Streets that often flood during peak monsoon start to dry, so exploring markets, temples, and riverfront spots gets easier.
With shorter rain showers and longer days, fall really sets the mood for the months ahead.
Overview of Fall Climate in Phnom Penh
You’ll get warm temps, high humidity, and a steady shift from heavy rain to drier skies during fall in Phnom Penh.
The season brings a real change in weather and daily life, so it’s good to know what to expect if you’re planning a visit or a move.
Seasonal Weather Patterns
During fall, Phnom Penh’s daily highs average about 88°F (31°C). Nights don’t cool off much, usually staying near 77°F (25°C).
Highs rarely go below 81°F or above 93°F, and lows mostly fall between 70°F and 80°F.
Humidity? It’s almost always high. Muggy air sticks around most days.
Even as rain drops off, you’ll still feel that sticky air. It’s just part of the deal here.
Cloud cover starts heavy—about 90% overcast at the beginning of fall. By late November, it drops closer to 60%.
So, you gradually get more clear days as the season goes on.
Transition from Rainy to Dry Season
Fall acts as the bridge between Cambodia’s rainy and dry seasons. September still brings a lot of rain, with about 7 inches over 31 days.
By November, rainfall drops sharply to just 1–2 inches.
The chance of a wet day falls from around 62% in early September to only 19% by late November.
So, September is the wettest part of fall, but November feels much more comfortable for being outdoors.
Daylight hours shrink too. Early September gives you about 12 hours and 20 minutes of daylight, but by late November, it’s down to 11 hours and 30 minutes.
Sunsets move earlier, from around 6:10 PM in September to about 5:32 PM in November.
Comparison with Other Seasons
Compared to the hot season in April, when highs often hit 96°F (36°C), fall feels more moderate.
Nights stay warm, but you dodge the extreme heat that peaks in late spring.
Against the winter months (December–February), fall is still wetter and more humid. Winter brings clearer skies, cooler nights, and a more pleasant vibe for travelers.
Unlike the summer monsoon, which dumps heavy rain, fall shows a clear drop in rainfall.
So, you still get the humidity, but fewer big storms.
Warm temps, less rain, and clearer skies give fall its own spot in Phnom Penh’s yearly weather cycle.
Average Temperatures During Fall
Phnom Penh stays warm all through fall, with only small shifts in highs and lows.
You’ll get steady heat during the day, mild nights, and a slow cooling trend as the season moves along.
Daytime and Nighttime Temperature Ranges
During fall, daytime temps usually sit around 88°F (31°C). Highs almost never drop below 81°F (27°C) or go above 93°F (34°C).
So, you’ll almost always feel warm or hot.
At night, lows average about 77°F (25°C). Temperatures rarely fall below 70°F (21°C), so evenings stay humid and muggy.
Unlike places where nights cool off a lot, Phnom Penh nights just aren’t that much different from the day.
This small gap between highs and lows is classic tropical climate.
Plan on wearing light clothes all the time—jackets are pretty much useless here. Air conditioning or a good fan is your friend.
Monthly Temperature Trends
From September to November, temps shift a bit. September is the warmest, with highs near 89°F (32°C) and lows around 78°F (26°C).
Rain is still common, which bumps up the humidity.
October cools off just a touch, with highs closer to 87°F (31°C) and nights around 76°F (24°C). Humidity starts to drop as the rains ease up.
By November, things feel a little cooler and drier. Highs average 86°F (30°C), and lows hover near 75°F (24°C).
November’s usually one of the nicer months for being outside, though the difference isn’t huge.
Record Highs and Lows
Averages don’t tell the whole story. The hottest days in Phnom Penh can hit 96°F (36°C), but that’s rare in fall.
On the flip side, the coolest fall temps barely dip below 70°F (21°C). Even then, it’s still humid—don’t expect crisp or chilly air.
Against the year’s extremes—like 104°F (40°C) in the hottest months and 73°F (23°C) in the coolest—fall weather is pretty moderate.
You won’t get wild temperature swings, but the steady warmth means you should always be ready for heat and humidity.
Rainfall and Humidity in Autumn Months
During autumn in Phnom Penh, you’ll see heavy rain early on, then a steady drop in both precipitation and humidity.
The move from wet monsoon to drier months shapes how comfortable each day feels, how easy it is to travel, and what you can do outside.
Monthly Rainfall Totals
Rainfall stays high in September, averaging about 250 mm over 18–20 rainy days. It’s the wettest month of the year.
Streets can flood fast, especially in low spots, so plan for extra travel time.
By October, rainfall drops to around 130–150 mm, with about 12–15 rainy days. Showers are still common, but they’re usually shorter and less intense.
November brings a bigger decline, with totals falling to 50–70 mm and fewer than 7 rainy days.
That’s when the wet season finally lets go, making it easier to get outside.
| Month | Avg. Rainfall (mm) | Rainy Days (approx.) |
|---|---|---|
| September | ~250 | 18–20 |
| October | ~140 | 12–15 |
| November | ~60 | 5–7 |
Humidity Levels and Effects
Humidity sticks around in September, often above 80%. The heat feels heavier, and you’ll notice dampness indoors.
Clothes and gear dry slower, which can be annoying.
In October, humidity starts to ease a bit, averaging between 75–80%. Less rain helps, but the air still feels sticky, especially on cloudy days.
Staying hydrated and wearing light fabrics makes a real difference.
By November, humidity drops closer to 70%. That makes a noticeable difference.
With less rain and lower humidity, you can spend more time outside without feeling bogged down by the weather.
End of Monsoon and Onset of Dry Season
November really marks the change. The southwest monsoon fades, and drier northeast winds start to take over.
This shift cuts down both rainfall and humidity, signaling the start of the dry season.
For travel, you get more predictable weather. Flood risks drop, roads dry out faster, and river levels stabilize.
This change also helps agriculture, with rice harvesting lining up as the heavy rains end.
By late November, you’ll see clearer skies, more sun, and much better outdoor conditions.
Sunshine, Cloud Cover, and Wind Patterns
In fall, Phnom Penh gets shorter days, less sunshine, and more cloud cover compared to the dry season.
Wind speeds mostly stay light to moderate, but seasonal shifts bring some small changes.
Average Sunshine Hours
Sunshine drops as fall goes on. In September, you’ll get about 4 to 5 hours of sun per day—that’s actually some of the lowest for the year.
By November, skies clear up a bit, and you get closer to 6 to 7 hours of sunshine each day.
The pattern follows the end of the wet season. September’s heavy rain and clouds limit sunlight, but by November, drier air brings brighter days.
Cambodia averages around 2,500 hours of sunshine a year, but fall doesn’t contribute as much as the dry months.
If you want to plan outdoor stuff, late fall is your best bet.
| Month | Avg. Daily Sunshine | Notes |
|---|---|---|
| September | 4–5 hours | Wettest month, frequent storms |
| October | 5–6 hours | Transition period |
| November | 6–7 hours | Drier, clearer skies |
Cloud Cover Trends
Cloud cover stays high in early fall. September brings a lot of overcast skies thanks to the monsoon.
You’ll get fewer clear days and more gray ones, even when it’s not raining.
By October, clouds start to break up. There are still plenty of partly cloudy afternoons, but fewer days are totally overcast.
November brings much clearer skies as the dry season arrives.
This change is gradual. In October, weather can flip from cloudy to sunny in just a few hours.
Typical Wind Speeds
Winds stay light and steady through fall. They usually range from 2 to 3 meters per second (about 4–7 mph).
These breezes aren’t strong, but they do help with the heat and humidity.
September and October are usually calmer, with lighter winds during the wettest weeks.
By November, winds pick up a bit as the region shifts into the dry season.
Wind direction also changes. During the monsoon, winds blow mostly from the southwest, bringing moisture.
By late fall, they shift to the northeast, bringing in drier air. That’s why November feels more comfortable outside.
Weather Impacts on Daily Life and Travel
Fall weather in Phnom Penh really affects how you get around and plan your days.
Rain, humidity, and heat can change transportation, comfort, and when you want to be outside.
Flooding and Urban Conditions
Heavy rain in September and October often leads to street flooding in Phnom Penh.
City drainage struggles to keep up, so some roads stay waterlogged for hours.
This slows traffic, adds time to your trips, and makes walking tricky.
Motorbike rides get riskier when potholes fill with water. It’s tough to judge how deep the water is.
Tuktuks and cars sometimes get stuck, especially in low neighborhoods.
Flooding can mess with daily errands too. Markets usually stay open, but muddy paths and standing water make shopping a hassle.
If you’re heading to temples, museums, or the riverside, expect delays moving between spots.
Carrying light rain gear, waterproof shoes, and keeping electronics in plastic bags helps you adapt.
Staying flexible with your plans makes getting around a lot easier during this part of the season.
Best Times for Outdoor Activities
By late October and November, rainfall drops off pretty fast. Streets dry out more quickly, and sudden downpours become rare.
You’ll probably find sightseeing, walking tours, and river cruises a lot more comfortable. Average highs stick around 86–88°F (30–31°C), but the humidity finally starts to let up.
Early mornings and evenings feel nicest for a stroll by the Tonle Sap River or just wandering through Phnom Penh’s parks. If you’re into cultural visits, this is a solid time to check out temples or the Royal Palace without slogging through heavy rain.
Outdoor cafés and rooftop dining get a lot more appealing when the skies clear up. Plan longer day trips, like heading to the Killing Fields or out to countryside villages, during the drier weeks in November.
You’ll dodge flooded roads and won’t have to waste time waiting for the weather to turn.
Regional and Climatic Context
Phnom Penh’s fall climate really shows its tropical monsoon roots, and the city’s spot along the Mekong and Tonlé Sap rivers matters a lot too. If you want to understand the patterns, you’ll need to see how the capital stacks up against the rest of Cambodia and Southeast Asia.
Phnom Penh Compared to Other Cambodian Regions
When you visit Phnom Penh in the fall, you’ll feel the warmth—temperatures usually stay between 29°C and 32°C (84–90°F). Rainfall stays high in September but drops off sharply by November.
The city feels a bit more comfortable than during the earlier wet season. Compared to Siem Reap up in the northwest, Phnom Penh tends to feel a bit more humid because of its lower elevation and those rivers.
Siem Reap cools off faster at night, but Phnom Penh keeps its warmth longer. Sihanoukville and the southern coast get hammered by heavier rainfall in the fall, sometimes double what Phnom Penh gets.
Coastal storms can really mess up travel plans down there, while the capital usually just has shorter, less annoying showers. The northeastern provinces like Ratanakiri run cooler and wetter than Phnom Penh.
Those highland spots get more clouds and less sun, but Phnom Penh still averages about 6–7 hours of sun per day by late fall. So, if you’re in Phnom Penh, you get a bit of everything: you skip the worst coastal rains and the chilly, gloomy highlands, and by November, you’re actually getting some nice dry days.
Phnom Penh’s Climate in the Context of Southeast Asia
The Southwest Monsoon shapes Phnom Penh’s fall weather and sets the tone for much of Southeast Asia. From May to October, heavy rain sweeps through the city, and September usually brings the most downpours.
By November, the monsoon pulls back, so the skies get clearer and the air feels drier.
Phnom Penh usually feels a bit warmer and more humid than Bangkok. Still, rainfall totals don’t differ much, and both cities head into a drier, more pleasant stretch as fall wraps up.
When you compare it to Hanoi, the difference jumps out. Northern Vietnam cools down pretty quickly in autumn, with temperatures slipping into the low 20s °C (70s °F). Phnom Penh, on the other hand, stays hot almost all the time, barely budging from its usual warmth.
Go further south to Ho Chi Minh City and you’ll spot a nearly identical pattern to Phnom Penh. Rain tends to linger longer into November there, though. Phnom Penh dries out a little earlier, so you can count on better outdoor weather by mid to late fall.
So, Phnom Penh really does share the same monsoon cycle as its neighbors. Still, its quicker shift to dry weather makes it, in my opinion, one of the nicer urban spots to visit in mainland Southeast Asia as fall winds down.