Siem Reap records about 1365mm of rain across roughly 102 wet days a year, which is a 28% chance on an average day. September is the wettest month at 235mm (17% of the annual total) and January the driest at 4mm. Local rain type: monsoon. Siem Reap's monsoon (May-October) floods Angkor Wat's moats — the temples look spectacular but trails become muddy. Dry season is most comfortable.
Chance of rain on an average day: 28%
Rainfall climatology for Siem Reap. The live hour-by-hour answer for today loads at the top of this page from Open-Meteo and refreshes through the day — the figures below describe a typical year, not today.
Last updated: · Live forecast data refreshes hourly.
| Annual rainfall | 1365mm |
| Rain days per year | 102 |
| Odds on an average day | 28% |
| Wettest month | September — 235mm over 18 days |
| Driest month | January — 4mm over 1 days |
| Rain type | monsoon |
| Best dry window | November through March offers dry, comfortable weather for temple exploration. |
| Worst rain window | August through October brings the heaviest monsoon rain. |
September delivers 5775% more rain than January (235mm vs 4mm). That gap is the difference between planning around showers and ignoring them.
No single month holds more than 17% of the annual total, so rain in Siem Reap is spread through the year — there is no season you can rely on being dry.
Siem Reap rain arrives in short, heavy bursts — shelter and timing matter more than gear.
Rain falls on about 18 days in September against 1 in January — the frequency swing matters more for planning than the millimetre totals.
Climate normals. Use them to judge whether today's live forecast at the top of the page is typical or unusual for the season.
| Month | Rainfall | Rain days | Chance on a given day | Highs |
|---|---|---|---|---|
| January | 4mm | 1 | 3% | 31°C |
| February | 7mm | 1 | 3% | 31°C |
| March | 30mm | 2 | 7% | 32°C |
| April | 60mm | 5 | 17% | 32°C |
| May | 145mm | 11 | 37% | 34°C |
| June | 170mm | 13 | 43% | 34°C |
| July | 195mm | 15 | 50% | 35°C |
| August | 210mm | 16 | 53% | 35°C |
| September | 235mm | 18 | 60% | 34°C |
| October | 198mm | 15 | 50% | 34°C |
| November | 68mm | 5 | 17% | 32°C |
| December | 15mm | 1 | 3% | 32°C |
Rain probability is the chance that at least 0.2mm falls at your location — not how long it rains. For Siem Reap we combine the hourly probability curve, expected volume in millimetres, and the city's own rainfall record into a single umbrella verdict.
| Factor | Weight | What it measures |
|---|---|---|
| Hourly probability | 40% | Peak and sustained chance of measurable rain across the next 24 hours. |
| Expected volume | 30% | Total millimetres, which separates a passing shower from a genuine soaking. |
| Timing & duration | 20% | When rain starts, when it eases, and the longest continuous dry window. |
| Local rain type | 10% | Drizzle, brief showers, thunderstorms or monsoon — each needs different gear. |
Live hourly values come from Open-Meteo and refresh through the day. Monthly rainfall figures are climate normals, so they describe a typical year rather than a forecast.
Siem Reap records rain on roughly 102 days a year — about a 28% chance on any given day — totalling around 1365mm.
September, with about 235mm over 18 rain days. That is 17% of the entire year's rainfall in a single month.
January is the driest month at 4mm across roughly 1 days. November through March offers dry, comfortable weather for temple exploration.
Siem Reap's monsoon (May-October) floods Angkor Wat's moats — the temples look spectacular but trails become muddy. Dry season is most comfortable.
No. Probability is the chance that at least 0.2mm of rain falls at your location at some point in the period. Check the expected millimetres alongside it: 40% with 0.4mm is a passing shower, 40% with 12mm is a soaking.