Siem Reap in September
In September, Siem Reap averages 31°C (88°F) during the day and 25°C (77°F) at night, with frequent rain — about 18 days of the month see precipitation (275 mm total).
ShoulderConditions are warm and beach-friendly. Expect daily rain or showers, often in heavy bursts.
September is one of the wetter and less comfortable months in Siem Reap. If your dates are flexible, consider a different time of year.
How September compares to the rest of the year in Siem Reap
September is in the middle of the year for warmth in Siem Reap (9th of 12) and one of the wettest months (2nd of 12). Daytime temperature runs 2°C below the annual average (33°C). September runs 1°C cooler than August (32°C) and stays flat into October.
September sunrise & sunset in Siem Reap
Times shown for Siem Reap local time (Asia/Phnom_Penh), calculated for the 15th of September. They shift by a few minutes day to day across the month.
Photography light in Siem Reap — September
Golden-hour and blue-hour windows for the 15th of September, in Siem Reap's local time. Use these for soft warm light (golden) or cool architectural twilight (blue).
📅 When to book — Siem Reap in September
Travel writers usually only tell you when to go. Here's when to book flights and lodging for the best mix of price and availability, based on September's tier (Shoulder) and Siem Reap's popularity.
Crowds & pricing — September in Siem Reap
Siem Reap is in a shoulder season month — fewer crowds, slightly lower prices, and a calmer atmosphere than peak weeks. Most major sights stay open with normal hours, though a handful of seasonal restaurants or boat trips may run reduced schedules. Many regulars consider these months the best time to visit because you trade a small amount of weather reliability for a much more pleasant on-the-ground experience.
Sun & mosquito risk — September in Siem Reap
UV is a clear-sky sea-level estimate — clouds, altitude, and reflective surfaces (snow, water) shift it ±30%. Mosquito risk is climate-derived only; for current disease advisories (dengue, malaria, zika) check the CDC or WHO travel pages before your trip.
Siem Reap in other months
| Month | Avg high | Avg low | Rainfall | Rain days | Snow days |
|---|---|---|---|---|---|
| January | 32°C / 90°F | 20°C / 68°F | 5 mm | 1 | 0 |
| February | 33°C / 91°F | 21°C / 70°F | 5 mm | 1 | 0 |
| March | 35°C / 95°F | 23°C / 73°F | 30 mm | 3 | 0 |
| April | 35°C / 95°F | 25°C / 77°F | 90 mm | 7 | 0 |
| May | 34°C / 93°F | 25°C / 77°F | 170 mm | 11 | 0 |
| June | 33°C / 91°F | 25°C / 77°F | 210 mm | 15 | 0 |
| July | 32°C / 90°F | 25°C / 77°F | 200 mm | 16 | 0 |
| August | 32°C / 90°F | 25°C / 77°F | 230 mm | 18 | 0 |
| September | 31°C / 88°F | 25°C / 77°F | 275 mm | 18 | 0 |
| October | 31°C / 88°F | 24°C / 75°F | 260 mm | 15 | 0 |
| November | 31°C / 88°F | 23°C / 73°F | 135 mm | 9 | 0 |
| December | 31°C / 88°F | 21°C / 70°F | 30 mm | 3 | 0 |
Other cities with similar September weather
🌍 See the full ranked list of climate twins for Siem Reap in September →
Frequently asked questions
How hot is Siem Reap in September?
In September, Siem Reap averages a high of 31°C (88°F) and a low of 25°C (77°F) — generally hot.
Does it rain a lot in Siem Reap in September?
September is quite rainy in Siem Reap, with about 18 rainy days on average.
Is September a good time to visit Siem Reap?
September is hot but on the rainy side. It suits travelers who are comfortable with hot weather; check the month-by-month ranking to compare it against the rest of the year.
What should I pack for Siem Reap in September?
Pack lightweight, breathable clothing, sunglasses and sunscreen, plus a compact umbrella or rain jacket. See the full September packing list for Siem Reap for a complete, climate-based checklist.
Check the live 10-day forecast and sunrise/sunset.