Siem Reap weather by month
Siem Reap runs from about 25°C in December to 33°C in April, with July the wettest month at 323 mm.
warmest month
April
33°C
coolest month
December
25°C
wettest month
July
323 mm
worst air month
April
28 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 26°C | 2 mm | 328 h | 20 |
| February | 28°C | 26 mm | 316 h | 23 |
| March | 30°C | 55 mm | 338 h | 22 |
| April | 33°C | 28 mm | 354 h | 28 |
| May | 30°C | 225 mm | 292 h | 14 |
| June | 29°C | 163 mm | 280 h | 7 |
| July | 27°C | 323 mm | 210 h | 7 |
| August | 28°C | 197 mm | 315 h | 7 |
| September | 27°C | 317 mm | 230 h | 7 |
| October | 27°C | 289 mm | 274 h | 8 |
| November | 27°C | 97 mm | 308 h | 10 |
| December | 25°C | 29 mm | 305 h | 9 |
About 3,550 hours of sun a year. Roughly 173 rainy days a year.
These are long-run climate normals, not a forecast. A given year can sit well outside them. PM2.5 is a global model: near the coast it counts sea salt as fine particulate and reads high against ground stations, sometimes by a factor of two. Use the shape of the year, not the absolute number.
where these numbers come from
- · Temperature, rainfall and sunshine: ECMWF ERA5 reanalysis climate normals via Open-Meteo (CC BY 4.0), fetched once and stored.
- · PM2.5: Copernicus CAMS reanalysis, monthly means. Modelled, not station readings; near coasts CAMS counts sea salt as PM2.5 and reads high.
Last reviewed 2026-05-22. Full method, licences and the list of sources we rejected are on the methodology page.