Climate and average weather in Siem Reap
In Siem Reap, the weather is oppressive, sweltering, wet, and partly cloudy and remarkably steady, with daytime highs holding near sweltering levels all year. The wettest stretch peaks around September.
Over the course of the year, the temperature in Siem Reap typically varies from 23°C to 35°C, and is rarely below 18°C or above 38°C. April is the hottest month of the year, while December is the coldest.
Based on the travel score, the best time of year to visit Siem Reap for warm-weather activities is from mid November to mid February.
- Hottest
- Apr
- 35°
- Coldest
- Dec
- 23°
- Wettest
- Sep
- 244 mm
- Driest
- Jan
- 9 mm
- Rain / yr
- 1289 mm
- 175 wet days
- Daylight
- 11.2–12.8 h
- shortest–longest
- Elevation
- 18 m
- 13.4°N
- Clearest
- Feb
- 38% cloud
Siem Reap is capital of the same named Cambodian province.
- Founded
- ~802 CE
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Siem Reap weather by month, at a glance
The whole year in one picture — sky, rain, humidity, temperature and travel score. Click any band to jump to its full chart.
Each stripe is one measure across the whole year, stacked so a single day reads top to bottom. The sky band runs overcast grey on top down to clear blue at the base — more blue means sunnier — followed by the rainfall curve, the humidity band, a temperature strip that tints each stretch of the year by how warm its average high is, and the travel-score line at the foot. Scan straight down any date to read that day across every measure at once; the score climbs highest around mid November to mid February.
Temperature through the year
Daily average highs and lows in Siem Reap, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
Temperatures in Siem Reap stay fairly even through the year, without a distinct hot or cool season. The warmest month is April, with an average high of 35°C and low of 27°C; the coolest is December, with an average low of 23°C and high of 30°C.
Days typically run about 7°C warmer than nights, with the widest day–night swing (around 8°C) in February.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 31 | 33 | 34 | 35 | 34 | 33 | 32 | 32 | 31 | 31 | 31 | 30 |
| Avg low (°C) | 23 | 24 | 26 | 27 | 27 | 27 | 27 | 26 | 26 | 25 | 24 | 23 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| Jan | 31 | 23 |
| Feb | 33 | 24 |
| Mar | 34 | 26 |
| Apr | 35 | 27 |
| May | 34 | 27 |
| Jun | 33 | 27 |
| Jul | 32 | 27 |
| Aug | 32 | 26 |
| Sep | 31 | 26 |
| Oct | 31 | 25 |
| Nov | 31 | 24 |
| Dec | 30 | 23 |
How hot and cold Siem Reap really feels
The felt-temperature range through the year — heat index on the day's high (summer humidity), wind chill on the night's low (winter wind). The dashed lines are the plain thermometer; the gap is how much hotter or colder it really feels.
On the hottest afternoons, once humidity is folded in, Siem Reap feels like about 43°C (around May 4). About 347 days a year carry some heat stress, and 193 of them tip into dangerous heat (feels-like above 39°C), peaking in May.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feels-like high (°C) | 33 | 35 | 39 | 42 | 43 | 41 | 40 | 40 | 39 | 38 | 35 | 32 |
| Air high (°C) | 31 | 33 | 34 | 35 | 34 | 33 | 32 | 32 | 31 | 31 | 31 | 30 |
| Feels-like low (°C) | 23 | 24 | 26 | 27 | 27 | 27 | 27 | 26 | 26 | 25 | 24 | 23 |
| Air low (°C) | 23 | 24 | 26 | 27 | 27 | 27 | 27 | 26 | 26 | 25 | 24 | 23 |
| Feels-like high (°C) | Air high (°C) | Feels-like low (°C) | Air low (°C) | |
|---|---|---|---|---|
| Jan | 33 | 31 | 23 | 23 |
| Feb | 35 | 33 | 24 | 24 |
| Mar | 39 | 34 | 26 | 26 |
| Apr | 42 | 35 | 27 | 27 |
| May | 43 | 34 | 27 | 27 |
| Jun | 41 | 33 | 27 | 27 |
| Jul | 40 | 32 | 27 | 27 |
| Aug | 40 | 32 | 26 | 26 |
| Sep | 39 | 31 | 26 | 26 |
| Oct | 38 | 31 | 25 | 25 |
| Nov | 35 | 31 | 24 | 24 |
| Dec | 32 | 30 | 23 | 23 |
Average hourly temperature in Siem Reap
A compact picture of the whole year, hour by hour: each column is a day, each row an hour, and the color is the modeled average temperature. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
Read left to right for the day of the year and top to bottom for the hour of the day; the color is the modeled temperature, cool blues through to hot reds on the same scale as the other charts. A vertical slice is a single day's swing — coolest just before dawn, warmest in the mid-afternoon — while a horizontal slice follows one hour across the seasons. The darker overlay marks night and the lighter one the twilight around sunrise and sunset. Colors run warmest on April afternoons, near 35°C, and coldest before dawn in December, near 23°C.
Siem Reap weather by month
Every month at a glance. Click a month for its detailed page.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 31° / 23° | 9 | 1.9 | 11.3 | 5.5 |
| Feb | 33° / 24° | 13 | 2.6 | 11.6 | 4.5 |
| Mar | 34° / 26° | 52 | 7.8 | 11.9 | 3.2 |
| Apr | 35° / 27° | 94 | 13.5 | 12.3 | 2.5 |
| May | 34° / 27° | 148 | 21.4 | 12.6 | 2.2 |
| Jun | 33° / 27° | 132 | 20.7 | 12.8 | 2.4 |
| Jul | 32° / 27° | 135 | 22.1 | 12.7 | 2.6 |
| Aug | 32° / 26° | 162 | 24.4 | 12.4 | 2.4 |
| Sep | 31° / 26° | 244 | 25.9 | 12.1 | 2.5 |
| Oct | 31° / 25° | 224 | 23.3 | 11.7 | 3.1 |
| Nov | 31° / 24° | 62 | 8.8 | 11.4 | 4.7 |
| Dec | 30° / 23° | 16 | 2.9 | 11.2 | 5.7 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Siem Reap gets about 1289 mm of precipitation a year. On a typical day the chance of rain is very wet, but that rises and falls sharply with the seasons.
The wetter season lasts 6.3 months, from around Apr 24 to Oct 31, peaking in September at about 89% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Dec 30.
September is the wettest month by volume, with 244 mm over about 26 wet days; January is the driest, with 9 mm.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 6 | 9 | 26 | 45 | 68 | 70 | 71 | 78 | 86 | 73 | 31 | 10 |
| Rain days | 2 | 3 | 8 | 14 | 21 | 21 | 22 | 24 | 26 | 23 | 9 | 3 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 6 | 2 |
| Feb | 9 | 3 |
| Mar | 26 | 8 |
| Apr | 45 | 14 |
| May | 68 | 21 |
| Jun | 70 | 21 |
| Jul | 71 | 22 |
| Aug | 78 | 24 |
| Sep | 86 | 26 |
| Oct | 73 | 23 |
| Nov | 31 | 9 |
| Dec | 10 | 3 |
Monthly rainfall
Over a full year, Siem Reap collects about 1289 mm of rain across 175 wet days — roughly 107 mm in an average month.
It doesn’t fall evenly. September is the wettest month with 244 mm, while January is the driest at just 9 mm. The three wettest months alone bring about 49% of the year’s total.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (mm) | 9 | 13 | 52 | 94 | 148 | 132 | 135 | 162 | 244 | 224 | 62 | 16 |
| Rain days | 2 | 3 | 8 | 14 | 21 | 21 | 22 | 24 | 26 | 23 | 9 | 3 |
| Rainfall (mm) | Rain days | |
|---|---|---|
| Jan | 9 | 2 |
| Feb | 13 | 3 |
| Mar | 52 | 8 |
| Apr | 94 | 14 |
| May | 148 | 21 |
| Jun | 132 | 21 |
| Jul | 135 | 22 |
| Aug | 162 | 24 |
| Sep | 244 | 26 |
| Oct | 224 | 23 |
| Nov | 62 | 9 |
| Dec | 16 | 3 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Siem Reap, the average share of the sky covered by clouds shows significant seasonal variation over the course of the year.
The clearer part of the year begins around October 25 and lasts for 6.1 months, ending around April 28. The clearest month is February, when the sky is clear, mostly clear, or partly cloudy 77% of the time on average.
The cloudier part of the year begins around April 29 and lasts for 5.9 months, ending around October 24. The cloudiest month is August, when it is overcast or mostly cloudy 93% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 69 | 77 | 69 | 48 | 21 | 10 | 12 | 7 | 8 | 28 | 54 | 60 |
| Cloudier (%) | 31 | 23 | 31 | 52 | 79 | 90 | 88 | 93 | 92 | 72 | 46 | 40 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 69 | 31 |
| Feb | 77 | 23 |
| Mar | 69 | 31 |
| Apr | 48 | 52 |
| May | 21 | 79 |
| Jun | 10 | 90 |
| Jul | 12 | 88 |
| Aug | 7 | 93 |
| Sep | 8 | 92 |
| Oct | 28 | 72 |
| Nov | 54 | 46 |
| Dec | 60 | 40 |
Daylight, sunrise and sunset
Hours of daylight through the year, with sunrise and sunset times.
The gold band is daylight — sunrise runs along its lower edge, sunset along the upper — so it widens toward summer and pinches toward winter, with night the dark area above and below. The longest day, around June 6, brings about 12 h 48 min of light; the shortest, around January 1, only 11 h 12 min — a swing of roughly 1 h 36 min.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 11.3 | 11.6 | 11.9 | 12.3 | 12.6 | 12.8 | 12.7 | 12.4 | 12.1 | 11.7 | 11.4 | 11.2 |
| Sunrise (AM) | 6:35 | 6:32 | 6:17 | 5:56 | 5:42 | 5:41 | 5:49 | 5:55 | 5:57 | 5:59 | 6:09 | 6:24 |
| Sunset (PM) | 5:53 | 6:06 | 6:11 | 6:14 | 6:19 | 6:28 | 6:32 | 6:22 | 6:01 | 5:40 | 5:31 | 5:37 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 11.3 | 6:35 | 5:53 |
| Feb | 11.6 | 6:32 | 6:06 |
| Mar | 11.9 | 6:17 | 6:11 |
| Apr | 12.3 | 5:56 | 6:14 |
| May | 12.6 | 5:42 | 6:19 |
| Jun | 12.8 | 5:41 | 6:28 |
| Jul | 12.7 | 5:49 | 6:32 |
| Aug | 12.4 | 5:55 | 6:22 |
| Sep | 12.1 | 5:57 | 6:01 |
| Oct | 11.7 | 5:59 | 5:40 |
| Nov | 11.4 | 6:09 | 5:31 |
| Dec | 11.2 | 6:24 | 5:37 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Siem Reap averages about 8 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 1 and 19 days.
The sunnier stretch runs 5.9 months, from around Oct 29 to Apr 25. The sunniest month is February, with roughly 18 sunny days (bright).
The greyest month is September, down near 1 sunny days — about 96% fewer than the February peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 16 | 17 | 16 | 9 | 3 | 1 | 1 | 1 | 1 | 4 | 11 | 12 |
| Sky | Bright | Bright | Bright | Mixed | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Mixed | Mixed |
| Sunny days | Sky | |
|---|---|---|
| Jan | 16 | Bright |
| Feb | 17 | Bright |
| Mar | 16 | Bright |
| Apr | 9 | Mixed |
| May | 3 | Gloomy |
| Jun | 1 | Gloomy |
| Jul | 1 | Gloomy |
| Aug | 1 | Gloomy |
| Sep | 1 | Gloomy |
| Oct | 4 | Gloomy |
| Nov | 11 | Mixed |
| Dec | 12 | Mixed |
Humidity comfort
Share of days at each humidity comfort level, based on the dew point — the measure that tracks how muggy it actually feels.
Humidity comfort is graded by the dew point — the temperature at which the air would be fully saturated — because it tracks how muggy it actually feels far better than relative humidity does. A low dew point feels dry and crisp; a high one feels sticky and oppressive no matter the reading on a humidity gauge.
Siem Reap is humid all year round — on a typical day the air feels at least humid, and there is no real dry season to wait for.
The stickiest month is April, when it feels muggy, oppressive or miserable about 99% of the time. Even in January, the mildest month, the air is dry or comfortable only 9% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Comfortable (%) | 8 | 5 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 6 |
| Humid (%) | 23 | 18 | 4 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 6 | 20 |
| Muggy (%) | 36 | 25 | 12 | 2 | 0 | 0 | 0 | 0 | 0 | 5 | 20 | 34 |
| Oppressive (%) | 28 | 46 | 59 | 34 | 11 | 16 | 24 | 21 | 8 | 21 | 42 | 32 |
| Miserable (%) | 3 | 6 | 24 | 64 | 89 | 84 | 76 | 79 | 92 | 73 | 32 | 7 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | Miserable (%) | |
|---|---|---|---|---|---|---|
| Jan | 1 | 8 | 23 | 36 | 28 | 3 |
| Feb | 1 | 5 | 18 | 25 | 46 | 6 |
| Mar | 0 | 1 | 4 | 12 | 59 | 24 |
| Apr | 0 | 0 | 0 | 2 | 34 | 64 |
| May | 0 | 0 | 0 | 0 | 11 | 89 |
| Jun | 0 | 0 | 0 | 0 | 16 | 84 |
| Jul | 0 | 0 | 0 | 0 | 24 | 76 |
| Aug | 0 | 0 | 0 | 0 | 21 | 79 |
| Sep | 0 | 0 | 0 | 0 | 8 | 92 |
| Oct | 0 | 0 | 1 | 5 | 21 | 73 |
| Nov | 0 | 0 | 6 | 20 | 42 | 32 |
| Dec | 1 | 6 | 20 | 34 | 32 | 7 |
Wind
Average wind speed through the year, banded into plain-language speed zones so a number reads as 'breezy' or 'calm' without knowing the scale.
This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.
Across the year, average wind speed in Siem Reap is typically calm, near 8 km/h, and varies little with the seasons.
The windier part of the year lasts 3.2 months, from around Jun 4 to Sep 9. The windiest month is August, averaging about 10 km/h (calm).
The calmer part of the year runs from around Sep 10 to Nov 30, with October the calmest month at about 7 km/h.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 8 | 8 | 8 | 7 | 7 | 9 | 10 | 10 | 8 | 7 | 8 | 9 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (km/h) | Feels | |
|---|---|---|
| Jan | 8 | calm |
| Feb | 8 | calm |
| Mar | 8 | calm |
| Apr | 7 | calm |
| May | 7 | calm |
| Jun | 9 | calm |
| Jul | 10 | calm |
| Aug | 10 | calm |
| Sep | 8 | calm |
| Oct | 7 | calm |
| Nov | 8 | calm |
| Dec | 9 | calm |
Hazard calendar for Siem Reap
When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.
Siem Reap sits in the Pacific typhoon belt; the season peaks July–October.
Siem Reap's rainy season runs May–October, when most of the year's rain falls.
Best time to visit Siem Reap
To characterize how pleasant the weather is in Siem Reap throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around early February, Siem Reap is still near the tail of its best-weather window — great conditions with the peak-season crowds already thinning.
Inferred from the travel-score curve; month-by-month visitor numbers are a planned addition.
The travel score favors clear, rainless days with daytime highs between 18°C and 28°C. Based on this score, the best time of year to visit Siem Reap for general outdoor tourist activities is from mid November to mid February, with a peak score in the last week of December.
The travel score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Travel score (0–10) | 5.5 | 4.5 | 3.2 | 2.5 | 2.2 | 2.4 | 2.6 | 2.4 | 2.5 | 3.1 | 4.7 | 5.7 |
| Rating | fair | fair | poor | poor | poor | poor | poor | poor | poor | poor | fair | good |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 5.5 | fair |
| Feb | 4.5 | fair |
| Mar | 3.2 | poor |
| Apr | 2.5 | poor |
| May | 2.2 | poor |
| Jun | 2.4 | poor |
| Jul | 2.6 | poor |
| Aug | 2.4 | poor |
| Sep | 2.5 | poor |
| Oct | 3.1 | poor |
| Nov | 4.7 | fair |
| Dec | 5.7 | good |
The beach/pool score favors clear, rainless days with daytime highs between 24°C and 34°C. Based on this score, the best time of year to visit Siem Reap for hot-weather activities is from mid November to mid March, with a peak score in the last week of December.
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
What to pack for Siem Reap, by month
Month by month, what's worth putting in the bag — from the temperature range, rain chance, sun and wind. Tap a month for a quick packing note.
Siem Reap packs about the same all year — highs hold near 35°C. Across the year the things worth having are light clothes, rain gear and sun protection.
In April, Siem Reap sees daytime highs around 35°C and nights near 27°C. Pack light clothes and sun protection. Worth having: rain gear. About 14 days see rain.
UV index (midday) in Siem Reap by month
Clear-sky midday UV index through the year, shaded by the WHO exposure levels — how much sun protection each month calls for.
Under clear skies, the midday UV index in Siem Reap peaks around August 16 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near November 22 at about 8 (very high).
The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 10 | 10 | 12 | 12 | 11 | 12 | 13 | 14 | 12 | 11 | 8 | 8 |
| Level | Very high | Very high | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Very high | Very high |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 10 | Very high |
| Feb | 10 | Very high |
| Mar | 12 | Extreme |
| Apr | 12 | Extreme |
| May | 11 | Extreme |
| Jun | 12 | Extreme |
| Jul | 13 | Extreme |
| Aug | 14 | Extreme |
| Sep | 12 | Extreme |
| Oct | 11 | Extreme |
| Nov | 8 | Very high |
| Dec | 8 | Very high |
Average hourly UV index in Siem Reap
Modeled clear-sky UV for every hour of every day — when in the day sun protection actually matters.
The whole year hour by hour: each column is a day, each row an hour, and the color is the modeled clear-sky UV index — the midday peak scaled down as the sun sits lower in the sky. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
UV falls off far faster than brightness as the sun drops, so even in August the burn window is concentrated in the middle of the day: about 8.5 hours a day reach index 3 (protection recommended), and 6.5 hours reach 6 or more. Mornings and late afternoons stay comparatively gentle year round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV ≥ 3 (h/day) | 7 | 7 | 8 | 8 | 8 | 8 | 8.5 | 8.5 | 8 | 7.5 | 6.5 | 6.5 |
| UV ≥ 6 (h/day) | 4.5 | 5 | 6 | 6 | 6 | 6 | 6.5 | 6.5 | 6 | 5 | 4 | 4 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 7 | 4.5 |
| Feb | 7 | 5 |
| Mar | 8 | 6 |
| Apr | 8 | 6 |
| May | 8 | 6 |
| Jun | 8 | 6 |
| Jul | 8.5 | 6.5 |
| Aug | 8.5 | 6.5 |
| Sep | 8 | 6 |
| Oct | 7.5 | 5 |
| Nov | 6.5 | 4 |
| Dec | 6.5 | 4 |
Air quality in Siem Reap by month
Average fine-particle pollution (PM2.5) through the year — so you can see which months the air is worst, not just the yearly average.
Air quality in Siem Reap is worst in February — around 40 µg/m³ PM2.5 (poor), about 2.9× the cleanest month (November, 14 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 29 | 40 | 40 | 37 | 19 | 15 | 16 | 15 | 15 | 17 | 14 | 14 |
| Level | Moderate | Poor | Poor | Poor | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 29 | Moderate |
| Feb | 40 | Poor |
| Mar | 40 | Poor |
| Apr | 37 | Poor |
| May | 19 | Moderate |
| Jun | 15 | Moderate |
| Jul | 16 | Moderate |
| Aug | 15 | Moderate |
| Sep | 15 | Moderate |
| Oct | 17 | Moderate |
| Nov | 14 | Moderate |
| Dec | 14 | Moderate |
Growing season
Siem Reap is frost-free year round — even the coldest nights rarely reach freezing, so there is no start or end to the growing season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 |
| Frost nights | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 100 | 0 |
| Feb | 100 | 0 |
| Mar | 100 | 0 |
| Apr | 100 | 0 |
| May | 100 | 0 |
| Jun | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 0 |
| Sep | 100 | 0 |
| Oct | 100 | 0 |
| Nov | 100 | 0 |
| Dec | 100 | 0 |
Growing degree days
Growing degree days tally heat above 10°C: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. Siem Reap banks about 6,880 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around April.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°C·days) | 523 | 516 | 623 | 624 | 635 | 599 | 604 | 598 | 561 | 562 | 525 | 510 |
| Growing degree days (°C·days) | |
|---|---|
| Jan | 523 |
| Feb | 516 |
| Mar | 623 |
| Apr | 624 |
| May | 635 |
| Jun | 599 |
| Jul | 604 |
| Aug | 598 |
| Sep | 561 |
| Oct | 562 |
| Nov | 525 |
| Dec | 510 |
Solar energy
Average daily shortwave solar energy reaching the ground, banded into brightness zones so the number means something at a glance.
Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.
Siem Reap receives about 5.3 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 4.5 and 6.2 kWh/m².
The brighter stretch of the year lasts 5.0 months, from around Jan 20 to Jun 19. The brightest month is April, averaging about 6.2 kWh/m² (intense).
The dimmest month is September, down near 4.6 kWh/m² — roughly 25% less than the April peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 5.2 | 5.8 | 6.1 | 6.2 | 5.8 | 5.4 | 5.1 | 5.0 | 4.6 | 4.7 | 4.8 | 4.8 |
| Level | Bright | Bright | Intense | Intense | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 5.2 | Bright |
| Feb | 5.8 | Bright |
| Mar | 6.1 | Intense |
| Apr | 6.2 | Intense |
| May | 5.8 | Bright |
| Jun | 5.4 | Bright |
| Jul | 5.1 | Bright |
| Aug | 5.0 | Bright |
| Sep | 4.6 | Bright |
| Oct | 4.7 | Bright |
| Nov | 4.8 | Bright |
| Dec | 4.8 | Bright |
Where is Siem Reap?
Siem Reap sits at 13.4°N, 103.9°E, 18 m above sea level, in Cambodia. The nearest listed city is Yeang, 34 km away.
What Siem Reap looks like
Topography around Siem Reap
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Siem Reap.
Within 3 km, the terrain around Siem Reap has only modest variations in elevation — a maximum elevation change of 28 m around an average of 17 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 123 m; within 80 km, significant variations in elevation — a maximum elevation change of 484 m.
The land around Siem Reap is covered by artificial surfaces (60%) and trees (24%) within 3 km, cropland (45%) and trees (30%) within 16 km, and cropland (48%) and trees (30%) within 80 km.
Cambodia travel facts
- Travel advisory
- Level 2
- Exercise Increased Caution
- Power plugs
- Type A / C / G
- 230 V · 50 Hz
- Prices
- ≈ 34% of US
- price level, 2025
- GDP per capita
- $2,872
- 2025
- Happiness
- 4.5 / 10
- World Happiness, 2025
- Safe drinking water
- 30%
- of population, 2024
- Homicide rate
- 1.8
- per 100k, 2011
- Road deaths
- 19.6
- per 100k/yr, 2019
- Income group
- Lower middle
- World Bank
- English
- Very low
- EF EPI 390
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Siem Reap (13.3618°, 103.8606°, elevation 18 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).