Spring in Siem Reap means hot days, warm nights, and humidity that creeps up as summer approaches. Daytime highs usually hover around 94°F, and nights rarely drop below 76–80°F. This is easily one of the hottest stretches of the year.
March heats up fast, and by April, the heat can feel relentless. That’s when the wet season starts to make itself known.
Clouds and rain arrive quickly, too. Early spring feels dry and sunny, but by May, most days bring thick clouds and sudden, heavy showers. This shift signals the end of the dry season and the start of Cambodia’s long monsoon period, which definitely affects both comfort and travel plans.
Daylight stretches out as spring goes on, giving you more hours to wander the temples or countryside before dusk. Humidity ramps up, and by late spring, every day feels sticky. If you know these patterns, you can plan a better balance between sightseeing and downtime, and set your expectations for the weather.
Overview of Spring Weather in Siem Reap
Spring in Siem Reap brings hot temperatures, climbing humidity, and a big jump in rainfall as the weeks go by. The days last longer, clouds roll in, and skies that start out dry in March become much wetter by late May.
Typical Weather Conditions
You’ll see daily high temperatures around 94°F (34°C), and in April, it sometimes spikes to 102°F (39°C). Nights don’t cool off much—76°F (24°C) in early March up to about 80°F (27°C) by May.
Humidity rises fast. By the end of spring, muggy afternoons make it feel hotter than the numbers say.
Rain picks up, too. March starts out dry, but by May, you’ll notice rain most days. Rainfall increases from less than 1 inch early in the season to almost 6 inches by the end.
Clouds follow the same pattern. March brings more blue sky, but May often stays cloudy or overcast.
Seasonal Variations in Spring
Spring weather in Siem Reap changes a lot. Early March is pretty dry and sunny. April? That’s the hottest month, no question. By May, the wet season gets underway.
Check out the seasonal shift here:
| Month | Avg High Temp | Avg Low Temp | Avg Rainfall | Sky Conditions |
|---|---|---|---|---|
| March | 93°F (34°C) | 76°F (24°C) | ~0.8 in | Partly clear |
| April | 95°F (35°C) | 79°F (26°C) | ~2.5 in | Increasing clouds |
| May | 94°F (34°C) | 80°F (27°C) | ~5.7 in | Mostly cloudy |
Daylight stretches out by almost an hour from March to May. That’s more time in the sun—and more time in the heat and humidity.
Comparison with Other Seasons
Compared to winter, spring is hotter, much more humid, and cloudier. January and February bring nights down to 70°F (21°C) and clearer skies, so outdoor activities feel easier.
Spring stays a bit drier than summer, but it’s still pretty humid. June through September gets the most rain, with frequent storms and plenty of soggy days.
Autumn feels different, too. Spring is hotter and has fewer storms. October and November remain wet, but things cool off, with temperatures dropping back to the mid-80s °F (around 30°C).
So, spring in Siem Reap really marks that shift from dry to monsoon, with extreme heat and fast-rising rain and humidity.
Temperature Patterns During Spring
Spring in Siem Reap means hot days, warm nights, and humidity that won’t quit. You’ll see temperatures shoot up after sunrise, stay high all day, and barely drop at night.
Average Hourly Temperature Trends
Throughout spring, the average hourly temperature stays warm to hot almost nonstop. Mornings start out around 76–78°F (24–26°C), and by mid-afternoon, it’s often 94–95°F (34–35°C).
The hottest hours hit between 1 PM and 4 PM. Even after sunset, the air cools off slowly, so evenings stay muggy.
Overnight, there’s not much relief. Temperatures often stick above 80°F until close to midnight. If you want to be outside, afternoons can feel brutal.
Daily Temperature Range
The daily high in spring averages about 94°F (34°C). Lows sit between 76–80°F (24–27°C). The difference between day and night is usually 14–18°F, which isn’t much compared to cooler places.
April really turns up the heat, sometimes hitting 102°F (39°C). By late May, the mix of heat and humidity makes things feel even more intense, even if the temperature doesn’t climb much higher.
Here’s a quick look:
| Month | Avg High | Avg Low | Range |
|---|---|---|---|
| March | 93°F | 76°F | 17°F |
| April | 95°F | 79°F | 16°F |
| May | 94°F | 80°F | 14°F |
Nights just don’t cool off much, so you’re really in the heat all the time.
Non-Freezing Temperatures
Siem Reap never gets freezing weather. In spring, the lowest it gets is well above 70°F (21°C). That’s great for year-round farming and travel—no frost or cold snaps to worry about.
Because nights stay warm, you won’t notice big swings in comfort from day to night. A muggy day is followed by a muggy night. Visitors should just plan for constant heat, no matter what time it is.
This lack of cold shapes how locals build homes, what they wear, and how they farm. Daily life revolves around managing the heat, not fighting the cold.
Growing Degree Days
Growing degree days (GDD) track heat that helps plants grow. In Siem Reap, GDD values jump by about 3,000°F units from March to May. That’s a lot of warmth for crops.
By late spring, GDD totals hit nearly 4,800°F units—way higher than temperate zones. That’s why rice, tropical fruits, and other heat-loving crops do so well here.
For travelers, this means you can count on it being hot. For farmers, it means planting and harvesting move fast, with barely a break. The spring heat challenges comfort but powers agriculture.
Precipitation and Rainfall Trends
Spring in Siem Reap clearly shifts from dry to wet. Rainfall climbs steadily, and wet days become more frequent, changing both daily life and travel plans.
Rainfall Amounts and Sliding 31-Day Rainfall
Rainfall starts light and ramps up. In March, you’ll see about 22 mm of rain. April averages around 65 mm, and by May, it jumps to more than 100 mm.
A sliding 31-day rainfall average really shows how fast things change. Early spring stays mostly dry, but by late May, the wet season is underway. This rolling measure helps you spot how quickly the weather flips.
Dry spells get shorter as rain increases. March can feel like an extension of the dry season, but by May, showers become frequent, especially in the afternoon or evening.
Wet Days and Rainy Season Onset
Wet days stack up as spring goes on. In March, you might only get 2 rainy days. By April, that jumps to around 5, and in May, it’s about 8.
A “wet day” means at least 1 millimeter of rain. This is handy to know if you’re planning outdoor stuff—one wet day can change plans.
By late May, the pattern of wet days says the rainy season has arrived. Expect more steady showers and rising humidity, though mornings often stay dry before storms roll in later.
Seasonal Precipitation Patterns
Spring rainfall in Siem Reap fits its tropical wet and dry climate. March is mostly dry, April brings a clear shift, and May marks the start of the wet season.
Rain doesn’t fall evenly. Early in the season, you’ll get bursts of showers followed by dry spells. By May, rain is heavier and more regular.
This change affects both farming and travel. Farmers welcome early rains for planting, but travelers need to prep for sudden storms, slick roads, and less sunshine as the wet season takes over.
Humidity and Comfort Levels
Spring in Siem Reap brings rising humidity as the dry season fades. This shift affects how hot it feels, how much you want to be outside, and how your body handles the climate.
Average Humidity Levels
Humidity starts lower in spring, then climbs. January and February stay around 50–55%. By March, it reaches about 58% and keeps rising through April and May.
The monsoon’s approach causes this jump. By late spring, humidity often sits above 65–70%, especially in May. The air just feels heavier as the months pass, even though temperatures stay hot.
In short:
- January–February: 50–55%
- March: ~58%
- April–May: 65–70%+
Early spring feels more manageable, but by late spring, it’s much more humid.
Humidity Comfort Levels
Humidity comfort depends on how your body handles heat and moisture. Early spring, with humidity around 55–60%, doesn’t feel as bad—even with highs near 95°F. You’ll sweat, but the drier air helps it evaporate.
By April and May, comfort drops. Humidity climbs toward 70%, and sweat just sits there. The same temperature feels way hotter. Travelers often call this time sticky or heavy, especially in the afternoons.
If you’re planning to be outside, mornings are your best bet. Evenings can feel better after sunset, but the humidity still hangs around. Drink water and wear light clothes—it helps.
Dew Point Trends
The dew point really shows how humid it feels. In Siem Reap’s spring, dew points run from the low 60s °F (16–18°C) early on to the low-to-mid 70s °F (21–23°C) by May.
- Below 60°F (15°C): Comfortable
- 60–65°F (16–18°C): You’ll notice the humidity
- 65–70°F (18–21°C): Muggy
- Above 70°F (21°C): Pretty oppressive
By late spring, dew points often stay above 70°F. That’s why the air feels so sticky. Even if the temperature doesn’t rise, the high dew point makes late spring one of the muggiest times of year in Siem Reap.
Cloud Cover and Sky Conditions
Spring skies in Siem Reap change fast. Early in the season, you’ll see more clear days, but by the end, clouds take over. Overcast days increase, blue skies become rare, and sunshine hours drop as the wet season rolls in.
Overcast and Mostly Cloudy Days
By mid to late spring, overcast and mostly cloudy skies take over in Siem Reap. At the start of March, you’ll see these conditions about half the time, but by late May, it’s more like 9 out of 10 days.
So, you shouldn’t expect much direct sunlight on most afternoons. The heavier cloud cover is a pretty clear sign that humidity and rainfall are on the way.
If you’re traveling, this can really shift your outdoor plans—especially if you want to visit temples or take a countryside tour. While the heat still packs a punch, the hazy skies make it tough to enjoy those long-distance views.
Key point: Overcast skies become the norm as spring moves along, changing both the look of the sky and how comfortable your activities feel.
Clear and Partly Cloudy Periods
Early spring still gives you a decent mix of clear or partly cloudy days. In March, skies are clear or mostly clear about half the time, so mornings feel brighter and you get better visibility.
These clearer spells are perfect for catching sunrises or sunsets at Angkor Wat. The light’s sharp and the air isn’t as heavy. By April, though, those chances start to disappear fast.
Even on the days with some clouds, strong sunlight often breaks through the gaps. That can actually make the heat feel even more intense, even if you get a little shade now and then.
Tip: If you’re after blue skies for photos, try to visit in early spring before the clouds really settle in.
Seasonal Cloud Cover Variation
Cloud cover changes fast as spring goes on. From March to May, the time spent under overcast or mostly cloudy skies jumps by more than 40%.
March usually gives you the best mix of sun and clouds. By April, the shift is hard to miss, and by May, cloudy skies just take over.
This change links up with rainfall patterns, too. As the clouds thicken, the chance of wet days goes up, and you can tell the rainy season is getting close.
Table: Cloud Cover Progression in Spring
| Month | Chance of Overcast/Mostly Cloudy | Chance of Clear/Partly Cloudy |
|---|---|---|
| March | ~49% | ~51% |
| April | ~70% | ~30% |
| May | ~91% | ~9% |
You’ll want to keep this pattern in mind when you plan your trip, so you know what to expect from the sky.
Sunlight, Daylight, and Solar Conditions
During spring in Siem Reap, the days slowly get longer, and the sun’s angle and strength shift as the season rolls on. You’ll spot changes in twilight, a steady drop in solar energy, and regular moon phases that shape what the night sky looks like.
Hours of Daylight and Twilight
You get almost an extra hour of daylight from early March to the end of May. On March 1, there’s around 11 hours 52 minutes, but by May 31, you’re up to 12 hours 51 minutes.
Sunrise comes earlier as spring goes on, moving from 6:20 a.m. in early March to 5:36 a.m. by the end of May. Sunset stretches a bit too, from 6:13 p.m. to 6:28 p.m.
Twilight—civil, nautical, and astronomical—gives you extra light before sunrise and after sunset. Civil twilight adds about 25–30 minutes on each end, which is handy for early temple visits or evening walks.
With more daylight and twilight, you’ve got longer windows for sightseeing, snapping photos, and getting outdoors during spring.
Solar Elevation and Energy
The sun climbs higher as spring goes on, hitting stronger midday heights by late May. This ramps up both the brightness and the heat you feel outside.
Average solar energy drops a bit through spring, from about 6.0 kWh per square meter in early March to 4.5 kWh by late May. More clouds and rising humidity block some of that direct sunlight.
At midday, the sun’s high enough to throw down harsh overhead light—tough for photos, but handy if you’re into solar power. Mornings and late afternoons bring lower angles, so the light’s softer and it’s not quite as hot.
If you pay attention to the sun’s angle, you can time your outdoor adventures for the most comfort—or just avoid the worst UV.
Moon Phases
The moon runs through its usual cycle—new, first quarter, full, and last quarter phases—during spring. These phases change how much moonlight you get at night, which can really matter if you’re planning something after dark.
A full moon lights things up, so you can walk around without needing much extra light. A new moon gives you dark skies, which is great if you’re into stargazing or night photography.
Moonrise and moonset times shift a lot during spring, sometimes by nearly an hour a day. If you keep an eye on these changes, you can plan your evening outings—especially if you want to see temples or the countryside under moonlight.
Wind and Atmospheric Conditions
Spring in Siem Reap brings heavier humidity, and the winds start to shift as the wet season creeps in. These changes affect how comfortable you feel and how likely you are to get caught in the rain.
Wind Speed and Direction
Most spring days, wind speeds in Siem Reap stay light or moderate, usually 5–10 mph (8–16 km/h). Strong gusts don’t happen often, but you’ll sometimes get a steady afternoon breeze.
The main wind direction swings slowly from northeast to southwest as the area moves from the dry season into monsoon time. Early spring brings drier northeast winds, but as months go by, you’ll notice more humid southwest winds coming from the Indian Ocean.
Breezes tend to pick up around midday when it’s hottest. Mornings and evenings are calmer, which makes being outside a lot nicer. Most travelers actually appreciate a light wind to take the edge off the heat, though the air still feels warm and sticky.
| Month | Prevailing Wind | Average Speed |
|---|---|---|
| March | Northeast | 6–8 mph |
| April | Variable | 7–9 mph |
| May | Southwest | 8–10 mph |
Influence on Weather Patterns
Wind direction really shapes spring weather. When northeast winds blow, things stay drier and you get fewer clouds. As southwest winds kick in, humidity rises and you’ll see more short, heavy showers.
By late May, the southwest monsoon brings in moist air, which bumps up cloud cover and rainfall in the area.
If you’re visiting, you’ll notice clearer skies and less rain in early spring, but things get much more unpredictable later. The constant flow of moist air makes the heat feel stronger, and evenings don’t cool off much.
Wind-driven changes in humidity and rain really mark the seasonal shift. If you’re planning outdoor trips, you’ll want to expect drier weather in March and be ready for more rain by May.
Geographical and Environmental Influences
Siem Reap’s spring climate doesn’t just come from seasonal weather patterns—the city’s geography matters too. The low elevation, a mix of farmland and urban areas, and the airport nearby all play a role in shaping heat, rainfall, and humidity this time of year.
Topography and Elevation
Siem Reap sits at about 23 meters (76 feet) above sea level on a flat floodplain near Tonle Sap Lake. This low elevation keeps temperatures pretty steady and warm.
Since the land’s flat, air moves gently. You don’t get the cooling breezes that higher places enjoy, so heat tends to hang around—especially in late dry season months like March and April.
Tonle Sap Lake also matters. Its big surface helps smooth out temperature swings, keeping nights a bit warmer and boosting humidity. As the wet season gets closer, you’ll really notice this effect.
Land Use and Surface Types
Most of the land around Siem Reap is cropland—mainly rice fields. These fields hold water during planting and early growth, which cranks up local humidity and makes afternoons feel even heavier.
Tree cover is scattered but makes a difference. Forest patches and shade trees around villages cool things down, while open fields and bare soil heat up fast in the sun. This mix creates small but real temperature differences from place to place.
Inside the city, artificial surfaces like roads and rooftops soak up heat during the day and let it out slowly at night. That’s why evenings usually feel warmer in town than out in the fields.
Role of Siem Reap International Airport
Siem Reap International Airport sits just a few kilometers from downtown. Its big runways and paved areas work like other urban spots, soaking up heat by day and releasing it at night.
The airport supplies reliable weather data for the region. Since the area’s flat and open, the weather instruments there give accurate readings for temperature, rainfall, and wind.
Planes themselves don’t really change the weather, but the cleared land around the airport cuts down on tree cover. That makes it a bit hotter and drier than the nearby farmland or shaded spots, especially in the dry spring months.
Data Sources and Climate Analysis Methods
Accurate climate info depends on good global datasets and detailed geographic measurements. You benefit from weather reanalysis models that blend satellite and ground data, plus mapping tools for land cover and elevation. These resources help explain Siem Reap’s seasonal patterns by balancing big climate trends with local geography.
MERRA-2 Reanalysis Data
The MERRA-2 reanalysis dataset pulls together long-term climate records by mixing satellite observations with ground measurements. It covers temperature, rainfall, humidity, and wind with high detail, so you can see how spring in Siem Reap stacks up against long-term averages.
Reanalysis pulls in lots of sources at once, not just single weather stations. That fills in data gaps and makes things more accurate, especially for places without many local measurements. For Siem Reap, it helps you see how the wet season starts each year and how things like cloud cover or rain intensity shift across March, April, and May.
MERRA-2 is handy for spotting extremes. You can check how often April heat waves top 40°C or how early-season storms add up for rainfall. If you’re planning a trip or looking into Cambodia’s climate patterns, these details actually matter.
Global Land Cover Share and Shuttle Radar Topography Mission
The Global Land Cover Share (GLC-SHARE) dataset shows different land use types like croplands, forests, and urban areas. In Siem Reap, you’ll notice both agricultural land and built-up zones, and this mix really affects local heat retention and how rain falls across the area.
You can use this data to check out how land cover changes microclimates around the city and near the Angkor temples. It’s honestly a handy way to see what’s happening on the ground, not just in theory.
The Shuttle Radar Topography Mission (SRTM) brings in elevation data with almost global coverage. Siem Reap sits at about 23 meters above sea level, so the terrain feels pretty flat and doesn’t do much to change the weather.
Still, SRTM data helps you map drainage patterns and figure out how seasonal rains spread across these low-lying spots. Sometimes it’s surprising how much you can learn from a simple elevation map.
GLC-SHARE and SRTM together give you a solid geographic context for climate data. When you combine land cover and elevation with reanalysis datasets, you get a better sense of how the physical environment shapes spring weather in this part of Cambodia.