When to Visit & Weather
Siem Reap Weather by Month: Heat, Rain and What It Does to Your Plans (2026)
April averages 35.8°C, September 288 mm of rain, December 20.7°C at dawn. Twelve months of Siem Reap weather, with the hours each month leaves for temples.
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Siem Reap’s weather comes down to three facts: it is hot in every month, it is very hot from March to May, and from May to October it rains most afternoons. The monthly averages that fill weather pages are accurate and almost useless on their own, because a 32°C high in January and a 32°C high in August are different days to spend on a temple terrace. What matters is the hour the heat peaks, the hour the rain arrives and how wet the air is.
Most weather-by-month pages print a temperature and a rainfall figure and stop. They leave out humidity, which turns September’s 31.7°C into a heavier day than January’s identical 31.7°C. They give rainfall in millimeters and not the hour it falls, which is the only thing that decides whether a temple morning survives. And they rarely connect the weather to the plans it changes: the sunrise time, the waterfall at Phnom Kulen, the level of the Tonle Sap, the mud at Beng Mealea.
This guide gives each month’s figures and what they mean for a day at Angkor, as a companion to the best time to visit Siem Reap, which weighs weather against crowds and prices. Climate figures are long-term monthly means from the Deutscher Wetterdienst record for Siem Reap, and sunrise times, park hours and lake levels were checked against official and operator sources in October 2026.
The Average Is Not the Day You Get
Three numbers sit behind every month, and only one of them gets printed.
The first is the high. Siem Reap’s average daily maximum ranges from 30.6°C in December to 35.8°C in April, a spread of barely five degrees. That small spread hides the real difference, which is the time of day the heat peaks and how long it lasts. In January the air is still near 20°C at dawn and stays pleasant until about 10:00 a.m. In April the night does not fall below 25°C and the stone terraces of the temples radiate heat from 10:00 a.m.
The second is humidity. Relative humidity averages 58 to 59 percent from January to April and climbs to 75 percent in September and October. At 75 percent humidity, sweat stops cooling the body efficiently, and a 31°C rainy-season afternoon feels closer to the April heat than the thermometer suggests. This is why travelers who check a September forecast and see January’s temperature are surprised.
The third is the hour of the rain. Siem Reap gets about 1,406 mm of rain a year, roughly 89 percent of it between May and October. Almost all of it falls as afternoon and evening storms. A month with 200 mm of rain usually still has dry mornings, which means a 5:00 a.m. temple start, the right way to see Angkor in any month, loses very little to the rain. The hours listed below for each month are a judgment drawn from those three figures, not a measurement.
The Year in Figures
| Month | High | Low | Rain | Rainy days | Humidity |
|---|---|---|---|---|---|
| January | 31.7°C (89°F) | 20.4°C (69°F) | 4 mm (0.15 in) | 1.5 | 59% |
| February | 33.5°C (92°F) | 22.4°C (72°F) | 5 mm (0.19 in) | 0.7 | 59% |
| March | 34.9°C (95°F) | 24.1°C (75°F) | 29 mm (1.1 in) | 3.2 | 58% |
| April | 35.8°C (96°F) | 25.4°C (78°F) | 57 mm (2.3 in) | 7.6 | 59% |
| May | 34.8°C (95°F) | 25.4°C (78°F) | 150 mm (5.9 in) | 17.0 | 66% |
| June | 33.6°C (93°F) | 25.1°C (77°F) | 214 mm (8.4 in) | 18.0 | 70% |
| July | 32.9°C (91°F) | 24.9°C (77°F) | 193 mm (7.6 in) | 17.6 | 71% |
| August | 32.4°C (90°F) | 25.1°C (77°F) | 209 mm (8.2 in) | 17.6 | 73% |
| September | 31.7°C (89°F) | 24.7°C (77°F) | 288 mm (11.3 in) | 17.4 | 75% |
| October | 31.5°C (89°F) | 24.5°C (76°F) | 200 mm (7.9 in) | 15.4 | 75% |
| November | 31.2°C (88°F) | 22.6°C (73°F) | 51 mm (2.0 in) | 6.4 | 68% |
| December | 30.6°C (87°F) | 20.7°C (69°F) | 7 mm (0.29 in) | 2.0 | 64% |
Figures are Deutscher Wetterdienst monthly means for Siem Reap. A rainy day is a day with measurable rain, often a single storm. The airport record counts more wet days in August, over 21, so treat the rainy-day column as a floor rather than a ceiling.
November to February: Cool and Dry
November
The month the rain stops. Rainfall drops to 51 mm over about six days, most of it in the first half, and humidity falls from 75 percent in October to 68 percent. The average high is 31.2°C and lows fall to 22.6°C. Sunrise is around 6:04 a.m. and sunset around 5:34 p.m., the earliest of the year, so a sunset at Pre Rup means being in place by 5:00 p.m. Usable hours outdoors: from 6:00 a.m. to about 11:30 a.m., and again after 3:30 p.m. The countryside is still green, the moats are full and the Tonle Sap is near its largest. The limitation: the first week can still deliver an afternoon storm, so keep the poncho until mid-month.
December
The coolest month and the clearest air of the year. Average high 30.6°C, average low 20.7°C, 7 mm of rain over two days and humidity at 64 percent. Sunrise is around 6:19 a.m. The 5:00 a.m. tuk-tuk ride is cool enough for a jacket. Usable hours: almost the whole day, with the hour after noon the only uncomfortable stretch on open terraces. The limitation is not weather but people: the last ten days of December bring the year’s peak crowds, which the December and January guide separates from the quieter first half.
January
The most comfortable month for a full temple day. Average high 31.7°C, average low 20.4°C, under 4 mm of rain over one or two days, and humidity at 59 percent. Sunrise is the latest of the year, around 6:31 a.m. on the 15th, which moves the sunrise pickup from 4:30 a.m. to about 5:15 a.m. Usable hours: from first light to about noon, and from 3:00 p.m. to closing. The limitation: the sun is strong by 9:00 a.m. on open stone, and the dry season has already started to shrink the lake.
February
The driest month: 4.7 mm of rain and less than one rainy day on average. The high rises to 33.5°C and lows to 22.4°C, so the jacket goes back in the bag by the second week. Humidity stays at 59 percent. Sunrise around 6:27 a.m. The weather is reliable, but the sky changes: farmers burn rice stubble across the plain, and from about the third week a white haze softens every view and dulls every sunrise into April. Usable hours shrink to about 6:00 to 11:00 a.m. and after 3:30 p.m. The limitation: photographers who want blue skies need the first half of the month.
March to May: The Heat
March
The month the heat arrives. Average high 34.9°C, with 36°C to 37°C afternoons by the third week, and lows of 24.1°C. Rain returns in small doses, 29 mm over about three days, usually a single evening storm that clears the haze for a morning. Humidity is the lowest of the year at 58 percent, which makes the heat dry and harsh rather than heavy. Sunrise around 6:11 a.m. Usable hours on open temples: before 10:30 a.m. and after 4:00 p.m. Between 11:00 a.m. and 3:00 p.m., the best time of day for each temple stops being advice and becomes a rule. The limitation: haze at its worst, and Phnom Kulen’s waterfall reduced to a trickle.
April
The hottest month, with an average high of 35.8°C (96°F), an average low of 25.4°C and 38°C to 40°C days common in the second half before the first storms. Rain averages 57 mm over seven or eight days, mostly in the last week, and arrives as violent pre-monsoon storms with wind and dust. Sunrise around 5:51 a.m. Humidity rises through the month, so late April feels heavier than March. Usable hours: 5:00 to 10:00 a.m., then nothing outdoors until about 4:00 p.m. The stone terraces of the Bayon and Pre Rup radiate heat by 10:00 a.m. The limitation: this is the month when heat exhaustion is a real risk for children and older travelers, and the April and May heat guide should be read as instructions.
May
The rains begin, the heat does not leave. Average high 34.8°C, average low 25.4°C, 150 mm of rain over 17 days, and humidity jumping to 66 percent. Sunrise around 5:38 a.m. The first storms of the season are the most violent: dust, wind and an hour of heavy rain between 3:00 p.m. and 6:00 p.m., then a cooler evening. Usable hours: 5:00 to 10:30 a.m., and the hour after a storm. The limitation: by late May the combination of 34°C and rising humidity is the most draining weather of the year, and the first rains turn the dirt tracks at Beng Mealea and Ta Nei to mud.
June to October: The Rains
June
The month with the earliest sunrise, around 5:37 a.m., and the longest dry mornings. Average high 33.6°C, low 25.1°C, 214 mm of rain over 18 days, humidity at 70 percent. The pattern is set: clouds build from about 1:00 p.m. and rain falls between 2:00 p.m. and 6:00 p.m. on roughly half the days. Usable hours: 5:00 a.m. to about 12:30 p.m., six or seven hours, more than in any dry-season month. The rice is being planted and the barays and moats are filling. The limitation: sunsets are a gamble, and the humidity makes 33°C feel like April.
July
Rain eases slightly to 193 mm over about 18 days, the high to 32.9°C, with humidity at 71 percent. Sunrise around 5:45 a.m. and the latest sunset of the year, around 6:35 p.m. on the 15th. Mornings are humid rather than hot. Usable hours: 5:30 a.m. to about 1:00 p.m. Angkor Wat’s moat is full and still, which gives the reflection dry-season visitors never see. The limitation: roughly one clear sunset in three, as the Angkor sunset guide explains.
August
The month with the most frequent rain: about 18 rainy days in the Deutscher Wetterdienst record and over 21 in the airport record, though the total, 209 mm, is less than September’s. Average high 32.4°C, low 25.1°C, humidity at 73 percent. Sunrise around 5:52 a.m. Storms are short and frequent. Usable hours: 5:30 a.m. to about 12:30 p.m. The Tonle Sap takes its biggest rise of the year and the flooded forest at Kampong Phluk becomes paddleable again, as the floating villages comparison explains. The limitation: Ta Prohm’s root-covered corridors and the paths at Beng Mealea are at their slipperiest.
September
The wettest month: 288 mm over about 17 days, the heaviest single storms of the year and humidity at 75 percent. The average high, 31.7°C, matches January’s, but the day feels nothing like January. Sunrise around 5:53 a.m. Some afternoons the rain starts at noon and continues into the night, and side streets in the Wat Bo and Sok San areas flood for a few hours after the worst storms. Usable hours: 5:30 to 11:30 a.m. on most days. The limitation: this is the month for a second pair of shoes and a dry bag, items the what to pack guide lists.
October
The month the rain loosens its grip, especially in the second half. Rainfall averages 200 mm over 15 days, humidity stays at 75 percent and the high is 31.5°C. Sunrise around 5:55 a.m. and sunset around 5:45 p.m. Storms shorten and start skipping days after mid-month. Usable hours: 5:30 a.m. to noon in the first half, longer in the second. The countryside is at its greenest, the Phnom Kulen waterfall at full volume and the Tonle Sap near its peak. The limitation: a week caught under the tail of a typhoon can be as wet as September, and no forecast a month ahead can say which week.
What the Weather Does to Each Plan
The temples. In every month the best hours at Angkor are the first ones, from the 5:00 a.m. park opening to about 10:30 a.m. From March to May the midday gap stretches from 11:00 a.m. to 3:00 p.m. From June to October the afternoon belongs to the rain. The three-day itinerary builds every day around that morning.
The sunrise. Sunrise at Angkor Wat moves from 5:37 a.m. in mid-June to 6:31 a.m. in mid-January. In the rainy season a clear dawn comes perhaps one morning in two or three, and in late February to April the haze turns the sun into a dull disc. The Angkor Wat sunrise guide sets pickup times by month.
Water at the sites. The rains of June to October fill the moats, the barays, the Tonle Sap and the rivers on Phnom Kulen. The lake swings from about 2,500 to 3,000 km² in April to as much as 16,000 km² around October and November. The Kulen waterfall is fullest from August to November and a trickle in March and April. Kbal Spean’s carved riverbed needs running water, which means the rainy season. The Tonle Sap lake guide gives the lake’s month-by-month level.
Roads and paths. Rain does more damage to the roads than to the temples. The road up Phnom Kulen is slippery after storms, the dirt approaches at Beng Mealea and Koh Ker turn to mud, and the paths at Ta Prohm get slick. Dry-season dust is the opposite problem: from December to April the roads east of town coat an open tuk-tuk in red powder.
By Situation
You cannot tolerate heat
December and January, then November and early February. Never mid-March to mid-May if there is a choice. If there is not, keep every temple before 10:30 a.m. and book a hotel with shade and a pool, as in hotels with a pool worth coming back to.
You hate rain more than heat
December to March, when the four months together average under 50 mm. Accept the crowds and peak prices of December to February, or the heat and haze of March.
You are traveling with small children
December or the first half of January, when dawns near 20°C and humidity near 60 percent make a morning manageable. Avoid April. For rainy-season trips tied to school holidays, the rainy day with kids guide covers the wet afternoons.
You want photographs
Late October to early December for green fields, full moats and clearing skies. January for hard clear light. August and September for wet dark stone and cloud. Avoid late February to April for haze.
You can only come in the rainy season
Plan the temples from 5:00 a.m. to 1:00 p.m., keep the afternoons flexible and treat a dry sunset as a bonus. The rainy season guide explains why many repeat visitors prefer it.
What It Actually Costs
The weather does not change the price of the Angkor Pass. It changes the small costs around the day.
| Item | Price | When it matters |
|---|---|---|
| Angkor Pass, 1, 3 or 7 days | $37, $62, $72 | Same in every month |
| Tuk-tuk, small circuit day | $18 to $25 | Any month, open to heat and rain |
| Car with driver, park day | $35 to $60 | March to May for air conditioning, June to October for shelter |
| Rain poncho | A dollar or two at a minimart | May to October |
| Water, 1.5 L at a minimart | About $0.75 (3,000 riel) | Every month, two or three bottles a person on hot days |
| Sunrise pickup surcharge | About $5 | Any month, earlier pickup from April to September |
| Second pair of shoes | Bring from home | August to October |
The largest weather cost is the vehicle. From March to May, a car with air conditioning between temples turns a half day into a full one, and the extra $15 to $35 over a tuk-tuk is the best money spent in those months. The getting around guide compares the options.
What Other Guides Get Wrong
- Printing temperature without humidity. September and January share a 31.7°C average high. At 75 percent humidity against 59, they are different days.
- Calling the rainy season a washout. Most rain falls as afternoon storms between 2:00 p.m. and 6:00 p.m. Mornings, when temples should be visited anyway, are usually dry.
- Treating the dry season as one season. November to February is cool. March to May is the hottest stretch of the year, with 38°C to 40°C days in late April. They need different plans.
- Ignoring the haze. From late February to April, stubble burning whitens the sky. Weather pages show it as sunny. Photographs show it as grey.
- Giving one sunrise time. It moves by nearly an hour, from 5:37 a.m. in June to 6:31 a.m. in January.
- Forgetting the dawn chill. December and January mornings average about 20°C, and a 5:00 a.m. tuk-tuk ride is cold enough for a jacket that also covers shoulders at the temples.
Addresses, hours, prices and transport times checked against operator websites and official sources in October 2026. Hours change seasonally and prices change often. Confirm anything time-critical with the operator.
Where to Go Next
The weather is one of five things that decide a travel month, and the best time to visit Siem Reap sets it against crowds, prices, festivals and the lake. For the two extremes in detail, read the April and May heat guide and the rainy season guide. For how many people will share the temples in each month, Angkor crowds by month does for visitor numbers what this page does for the thermometer, and the what to pack guide turns both into a list.
Addresses, hours, prices and transport times checked against operator websites and official sources in October 2026. Hours change seasonally and prices change often. Confirm anything time-critical with the operator. Found an error? Tell us and the guide's review date will be updated.
Frequently Asked Questions
What is the weather like in Siem Reap by month?
Siem Reap has three practical seasons. November to February is cool and dry, with highs of 30.6°C to 33.5°C and almost no rain from December to February. March to May is hot, with average highs of 34.8°C to 35.8°C and 38°C to 40°C days in late April. June to October is the rainy season, with highs of 31.5°C to 33.6°C, 190 to 290 mm of rain a month and humidity of 70 to 75 percent. The rain falls mostly as afternoon storms, so mornings stay usable in every month of the year.
What is the hottest month in Siem Reap?
April, with an average daily maximum of 35.8°C (96°F) and nights that average 25.4°C (78°F). March, at 34.9°C, and May, at 34.8°C, are close behind. In the second half of April individual days reach 38°C to 40°C before the first storms break the heat. Humidity rises through the month, so late April feels heavier than March at the same reading. Plan every open temple before 11:00 a.m. from March to May, spend 11:00 a.m. to 3:00 p.m. under a roof or in a pool, and use the last two hours before the park closes at 6:30 p.m.
What is the rainiest month in Siem Reap?
September, with an average of 288 mm (11.3 in) of rain over about 17 rainy days. June, August and October each average 200 to 215 mm, and July about 193 mm. The number of rainy days is roughly the same from May to September, 17 to 18 a month, but September's storms are the heaviest. Even then, rain tends to arrive as an afternoon or evening storm of one to three hours, often between 2:00 p.m. and 6:00 p.m. Some September days rain from noon to night, and side streets near Wat Bo and Sok San can flood for a few hours after the worst storms.
Is Siem Reap cold in December or January?
Not by most standards, but cooler than travelers expect. December nights average 20.7°C (69°F) and January dawns 20.4°C (68.7°F), with daily highs near 31°C. The cold moment is the open tuk-tuk ride at 5:00 a.m. to the Angkor Wat sunrise, when the wind makes 20°C feel chilly. A light jacket or long-sleeved layer is enough. It also covers shoulders for the temples. By 9:00 a.m. the jacket is off and the day is warm and dry, with humidity near 60 percent, the most comfortable conditions of the year for a full temple morning.
Does it rain all day in the rainy season in Siem Reap?
Rarely. The typical rainy-season day starts clear or cloudy, builds clouds from about 1:00 p.m., and delivers a storm of one to three hours between 2:00 p.m. and 6:00 p.m., often clearing before dark. From May to September about 17 or 18 days a month bring some rain, so roughly half the afternoons are wet. All-day rain happens mostly in September and early October, sometimes when the tail of a typhoon crosses the region. A temple day that runs from 5:00 a.m. to 1:00 p.m. loses very little to the weather in most rainy-season weeks.
When is the best weather to visit Angkor Wat?
December and January, for comfort. Highs near 31°C, dawns near 20°C, humidity around 60 percent and almost no rain make a full morning at the temples possible without a midday retreat. November and early February are close behind. The trade is that these months also bring the most visitors and the highest hotel rates. For photographs, late October and November add green landscapes, full moats and clearing skies, while late February to April brings haze from rice-stubble burning that turns the sky white. September has the darkest wet stone and the fewest people.