Understanding Siem Reap Weather: Sunshine, Seasons & Comfort

Siem Reap is hot all year round, and anyone who promises "cool mornings" every month is describing a short December window, not the climate. Once you accept that, the weather becomes predictable and easy to plan around: it is not four seasons, it is a hot-dry stretch, a hot-and-wet stretch, and a brief, genuinely pleasant cool period that residents treat as the reward for surviving the rest.

The temperature figures below are long-term monthly averages modelled for Siem Reap at 13.36°N, 103.86°E by the Swiss meteorological service meteoblue, using the ECMWF ERA5T dataset. Rainfall and humidity detail is from the climate-data publisher Weather and Climate, and the flood and disease warnings are from Australian Government Smartraveller advice.

The three seasons, honestly named

• Cool and dry (roughly November to February). The best window. Still warm by northern-hemisphere standards, but humidity drops and evenings are comfortable. December is the coolest month.
• Hot and dry (roughly March to May). The hardest stretch. April is the hottest month, with daily highs regularly past 35°C and sometimes spiking close to 40°C, in dry, dusty air.
• Green and wet (roughly May or June to October). The monsoon: humid, heavy but usually short downpours, and the greenest landscape of the year. September is the wettest month.

Month by month

Month	Typical daily maximum	Typical nightly minimum
January	31°C	22°C
February	33°C	24°C
March	34°C	26°C
April	35°C	27°C
May	34°C	27°C
June	33°C	27°C
July	32°C	27°C
August	32°C	26°C
September	31°C	26°C
October	31°C	25°C
November	31°C	24°C
December	30°C	22°C

What the table hides is humidity, and it is humidity, not the raw number, that decides how hot a day feels. Relative humidity is high much of the year — Weather and Climate records its lowest monthly average in March, around 58%, and its highest in September, around 75%.

Rain, and how disruptive it really is

Siem Reap averages roughly 1,470 mm of rain a year, concentrated in the monsoon. September, the wettest month, brings around 286 mm across roughly 18 rainy days; January, the driest, brings under 10 mm. The rain usually arrives as intense afternoon or overnight bursts rather than a grey all-day drizzle, which is why so many people still get things done through the wet season.

Be honest about the disruption, though. During heavy rain, streets can flood quickly, drains back up, and a ten-minute ride can become a wet half-hour. Smartraveller notes that Cambodia's wet season (it uses July to November) can bring severe storms and both seasonal and flash flooding, disrupting transport and essential services. Build slack into plans during the green season and keep a light rain jacket within reach.

Heat, humidity and staying comfortable indoors

The practical response to this climate is routine, not heroism:

• Do errands and exercise early, before about 9am, and again after the worst heat passes.
• Treat midday as indoor time. A siesta is a climate adaptation, not laziness.
• Drink more water than you think you need; heat and humidity dehydrate you quietly.
• Shade and airflow matter as much as temperature. A fan in a shaded room can beat a cold room in full sun.

Air-conditioning is how most people sleep, and its running cost is a real line item in a monthly budget — electricity here is priced higher than in many home countries, and an AC unit used every night adds up. Habits that keep the bill sane: set the unit to around 24-25°C rather than the lowest setting, close curtains against the afternoon sun, use a fan to move the cooled air, and cool the room you sleep in rather than the whole house. Our cost-of-living guide covers the budget implications.

What the rain means for your health

The wet season is also mosquito season, and Cambodia has dengue and other insect-borne diseases. Smartraveller advises repellent, long loose clothing, mosquito-proof accommodation, and in some areas antimalarial consideration. A ceiling fan and well-screened windows do more than most people expect, and knowing the local clinic options before you need them is part of living here well — see our healthcare guide.

Planning around the climate

Pack breathable light clothing, sun protection, a good rain shell for the green season, and one warm layer for the handful of genuinely cool December evenings. Whatever the month, expect one week that refuses to match the average. Our packing guide goes through this in detail.

Where VillageLife fits

VillageLife is a project in development in Siem Reap. Memberships and crowdfunding are not open yet. The climate is one reason the physical design of a long stay matters: shaded, well-ventilated spaces and dependable power make the hot months far more liveable, and we are designing around exactly that for future Members. The weather itself, of course, is not ours to change.