Siem Reap Climate by Month – Rainy Season, Temperature Averages

The climate figures for Siem Reap are averaged from 2016–2025 observations (10 years). Annual rainfall averages about 1,795 mm.

The rainy season runs April–November. The wettest month is September with 342.7 mm across 28 rain days; the driest is January at just 18.3 mm.

The hottest month is April (average high 34.4°C) and the coolest is December (29.9°C).

The most comfortable time to visit Siem Reap is January — less rain and milder heat.

Siem Reap is roughly 15% drier than Phnom Penh over the year but has a wider day-night temperature range because it sits further from the sea. For Angkor visitors, November to February is the window: dawn can drop to 18–20°C, cool enough to walk the temple complex for hours. In April the sandstone surface temperature can exceed 45°C at midday, which is why most itineraries split into an early-morning and a late-afternoon session.

— Ban biên tập KhmerMeteo · Meteorological data editors