Siem Reap Weather in December

🇰🇭 Cambodia

30°C

High

21°C

Low

Rain Days

10h

Sunshine

82%

Humidity

Asia › 🇰🇭 Cambodia › Siem Reap

Updated: March 2026

Is December a Good Time to Visit Siem Reap?

7/10

Good

December is a good time to visit Siem Reap (7/10). With 10 daily sunshine hours and only 3 rain days, this month delivers genuinely reliable outdoor conditions, ranking it 9th sunniest of the year in Siem Reap. Culture-focused travellers and those who prefer lighter crowds will find December a practical choice, with prices running lower than peak January without sacrificing all the good weather. January offers a similar profile at lower hotel rates if dates are flexible. The main practical note: Siem Reap's popular sites are busiest between 10am and 3pm regardless of season. Arriving at opening time or after 4pm makes a significant difference to the experience. Planning tips: accommodation is generally available without long lead times, and flight prices are typically lower than peak season. Flexible travellers will find the best deals by booking 2-4 weeks ahead. Mid-week arrivals consistently unlock lower hotel rates than weekend check-ins.

vs November:30°C avg high

The single most important thing to know about visiting Siem Reap in December: conditions are genuinely cooperative, with 30°C highs and only 3 wet days making this one of the more straightforward months to plan around. Precipitation totals 15mm for the month, spread across roughly 3 days, and 10 sunshine hours per day give you a reliable window for outdoor plans.

30°C

Avg High

21°C

Avg Low

3 days

Rain Days

10h

Sunshine

82%

Humidity

Temperature in Siem Reap in December

The 9°C day-night temperature range is typical for continental climates: a light jacket in the morning that you shed by midday and need again after sunset. At 82% humidity, the 30°C daytime high feels 2-4°C warmer in practice: quick-dry fabrics and shade-seeking between noon and 3pm are the sensible response. The UV index of 3 is low, meaning sun exposure is minimal concern and sunscreen is largely optional. Winds are calm at an average 13 km/h, so wind-chill is not a factor in planning your clothing. In Fahrenheit: 86°F average high, 70°F overnight low. Data sourced from Open-Meteo ERA5 climate reanalysis (1991–2020 normals).

Temperature in December

Monthly Precipitation (mm)

What to Wear in Siem Reap in December

Morning21°CBefore the day warms up

Afternoon30°CPeak daytime temperature

Evening24°CAfter sunset cools down

Packing for Siem Reap in December means dressing for 30°C days and 21°C evenings. A lightweight linen or cotton shirt with loose-fit trousers or a sundress handles the 30°C daytime heat. Evening temperatures settle at 21°C, a modest 9°C drop that a light cardigan or denim jacket covers. For footwear, breathable walking sandals work for casual exploration, but closed-toe trainers are better for uneven surfaces in the historic centre. For temple and religious site visits, carry a lightweight scarf or sarong to cover shoulders and knees, required at most major sites across the region. At 82% average humidity, quick-dry synthetic or bamboo fabrics dry overnight and stay comfortable longer than cotton.

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Local tip: Loose-weave linen and moisture-wicking fabrics are the practical choice in Siem Reap's heat and humidity. Many shopping centres run air conditioning at near-arctic levels, so a thin layer in your bag prevents discomfort indoors.

Events in Siem Reap in December

December has no major festivals or public holidays in Siem Reap, which is one of its practical advantages for independent travellers. Attractions run at lower capacity than during peak event periods, queues are shorter, and accommodation is easier to find without needing to book many months in advance. Local restaurants, markets, and transport operate at a relaxed pace, making this an ideal time for visitors who prefer a more authentic, unhurried experience of everyday city life rather than large crowds drawn in by a single major headline event.

What to Pack for Siem Reap in December

Based on 30°C average highs and 3 rainy days

Light layers for morning and evening
Breathable T-shirts and comfortable trousers
UV-protective sunglasses
Quick-dry travel towel
Anti-chafe balm for long walking days
Moisture-wicking synthetic fabrics for active days
SPF 30+ sunscreen
Comfortable walking shoes (a second pair lets the first air out overnight)
Universal travel adapter
Small day pack for city exploration
Reusable water bottle

Best Activities in Siem Reap in December

Early morning walk through Siem Reap's historic market districtBest before 9amTemperatures are still manageable at 26°C before the midday heat builds
Open-air rooftop dining at sunsetFrom 6pm onwardsThe 30°C daytime heat drops noticeably after sunset, making al fresco dining comfortable
Waterfront promenade or harbour walkEarly morning or after 5pmSea breezes cut through the humidity, making coastal routes the most pleasant in heat
Guided cycling tour of the old quarterFirst tour of the day (7-9am)The low-traffic window before tourist crowds and the cooler morning air make this the prime riding slot
Afternoon in a world-class museum or galleryAfternoon (2-5pm)Pairs well with outdoor morning activities and provides a mid-day rest from sightseeing
Coffee-house or traditional cafe culture experienceMid-morning or post-lunchA cultural ritual in this region that rewards slow appreciation regardless of weather
Evening live music, theatre, or opera performanceEvening shows typically at 7-9pmConsistent evening temperatures make getting to and from evening venues comfortable
Visit the main botanical garden or city park at seasonal peakYear-round; best light in morningDecember brings distinct seasonal changes to public green spaces worth exploring
Seek out chilled local specialities: cold-brew tea, ice desserts, or chilled seafood at street-level stallsAny time; most atmospheric in evening marketsHot-weather street food culture peaks in December, with vendors setting up specifically for warm evenings

Why is Siem Reap warm in December?

In December, Siem Reap sits in the dry season corridor, as the ITCZ shifts away from the region and trade winds bring drier, more stable air. This produces reliably sunny days reaching 30°C, with lower humidity than the wet months. Overnight lows of 21°C offer a pleasant reprieve from the midday heat. Climate data: Open-Meteo ERA5 (1991–2020).

Sunshine Hours

The average number of hours per day with direct sunlight. Calculated from satellite measurements. Days with more than 7 hours of sunshine are ideal for outdoor activities. Under 3 hours means overcast conditions dominate.

UV Index

A scale from 0-11+ measuring ultraviolet radiation intensity. UV 0-2: Minimal risk. UV 3-5: Moderate -- wear sunscreen. UV 6-7: High -- hat and SPF 30+ essential. UV 8-10: Very High -- limit midday exposure. UV 11+: Extreme -- seek shade between 10am-4pm.

Rain Days

A rain day is counted when precipitation exceeds 0.1mm. This threshold captures even light drizzle. Unlike total rainfall in mm, rain days tells you how often you might need an umbrella, which is useful for planning outdoor activities.

Humidity

Relative humidity as a percentage. Below 40%: Dry -- skin and throat may feel parched. 40-60%: Comfortable -- ideal for most people. 60-80%: Sticky -- light, breathable fabrics recommended. Above 80%: Muggy -- heat feels more intense; quick-dry clothing is essential.

Frequently Asked Questions: Siem Reap in December

In December, Siem Reap experiences average highs of 30°C (86°F) and lows of 21°C (70°F). Expect around 3 rainy days and 10 hours of sunshine per day, with humidity averaging 82%. The 9°C gap between daytime and overnight temperatures is worth planning around: light layers work for most visitors during the day, but an overshirt or cardigan handles the cooler evenings. UV exposure is moderate at index 3.

Siem Reap typically sees 3 rainy days in December, with total precipitation of around 15mm. This makes December one of the drier months of the year, and a reliable window for outdoor sightseeing and day trips. Rain showers tend to be brief when they do occur. For context, the driest month in Siem Reap typically sees 4-6 fewer rain days than December.

Pack lightweight, breathable clothing (linen or cotton), a wide-brim sun hat, SPF 50+ sunscreen, and a refillable water bottle for Siem Reap in December. The 30°C daytime heat demands sun protection during midday hours, typically 11am to 4pm. Rain is unlikely with only 3 wet days, so leave the umbrella at home and use the bag space for sunscreen. Quick-dry synthetic fabrics are preferable to cotton in 82% humidity.

Yes, December is an excellent time to visit Siem Reap. With 10 daily sunshine hours and only 3 rainy days, conditions are ideal for sightseeing and outdoor activities. Temperatures averaging 30°C during the day are comfortable for long walks and outdoor dining. This is peak travel season, so booking accommodation in advance and arriving at popular attractions early in the morning helps avoid the busiest periods.

The average high temperature in Siem Reap in December is 30°C (86°F), and the average low is 21°C (70°F). The mean daily temperature is approximately 26°C (78°F). The day-to-night range of 9°C is moderate, meaning a single light jacket covers most situations. These are 30-year climate normals based on the 1991 to 2020 reference period; individual years will vary, particularly in transitional months like spring and autumn.

The best month to visit Siem Reap is generally January. January offers the most sunshine at 11 hours per day and only 2 rainy days. Average temperatures reach 31°C, making it comfortable for sightseeing, outdoor dining, and exploring the city. If your travel dates are flexible, planning your trip around January gives you the best chance of dry, bright weather.

December is shoulder or low season in Siem Reap, meaning fewer tourists and generally lower prices than peak months. With 10 sunshine hours and 3 rainy days, the weather is less of a draw for mass tourism. This is an advantage for travellers who prefer a quieter, more relaxed experience with shorter queues and easier accommodation availability.

In December, Siem Reap suits a range of activities thanks to warm temperatures of 30°C. With few rainy days, outdoor activities are highly recommended. Top options include exploring historic neighbourhoods, visiting museums and galleries, local food markets, and day trips to surrounding areas. With 10 hours of sunshine, parks and waterfront walks are particularly enjoyable.

December ranks 9th sunniest of the year in Siem Reap, with an average 10 daily sunshine hours. The driest months are January, February, and December. March is the hottest month (34°C avg high); September is the coolest (30°C). From here, temperatures rise 1°C into January. Compared to last month (November: 30°C high, 9 rain days), December is similarly warm and drier. December sits in the middle of the annual sunshine ranking for Siem Reap, offering a reasonable balance of good weather and manageable crowds.

Year-Round Climate

Month	High	Low	Rain Days	Sun	Details
January	31°C	21°C	2	11h	View
February	33°C	23°C	3	11h	View
March	34°C	25°C	9	11h	View
April	34°C	26°C	15	11h	View
May	33°C	26°C	22	11h	View
June	32°C	26°C	21	10h	View
July	32°C	25°C	22	9h	View
August	31°C	25°C	25	9h	View
September	30°C	25°C	26	9h	View
October	30°C	24°C	23	10h	View
November	30°C	23°C	9	10h	View
December	30°C	21°C	3	10h	View

Other Months in Siem Reap

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Plan Your Trip to Siem Reap

Best Time to Visit Siem Reap Siem Reap vs Bangkok in December Siem Reap vs Ho Chi Minh City in December

Nearby Destinations with Similar Weather

These cities are within 500 km and experience broadly comparable weather conditions during the same calendar month, making them practical standalone alternatives or worthwhile additions to a longer regional itinerary.

Bangkok🇹🇭 Thailand364 km away

31°C21°C low

Ho Chi Minh City🇻🇳 Vietnam414 km away

30°C22°C low

Phnom Penh🇰🇭 Cambodia232 km away

31°C23°C low

Phu Quoc🇻🇳 Vietnam343 km away

28°C25°C low

Data Sources for Siem Reap

Siem Reap on Wikipedia Open-Meteo Climate API NOAA National Centers UK Met Office WMO GeoNames

Climate normals represent 30-year averages (1991-2020). Individual years may vary.