Weather in Siem Reap in August

A hard month. August is a hard month in Siem Reap, and worth planning around. You should expect rain on 24 days of the month, which is more days wet than dry.

August ranks 7 of 12 in Siem Reap: past the worst of the year but short of December, which is the month to book if the dates are open.

Rain on 24 of the month's 31 days, 6 of them heavy. At that frequency a wet-weather backup is not a contingency, it is the itinerary — book the indoor things first and treat the clear days as the bonus. Natural fibres and a second shirt for the day. At 86% nothing dries, including you.

What the averages hide

Averages flatten a month, and this one hides a few things: 20 days top 30 °C, making the heat continuous rather than occasional. Across the twenty years measured, the hottest August day reached 37.3 °C and the coldest night fell to 22.6 °C, and the wettest single day dropped 47 mm — roughly 24% of the month's rain in one day.

August is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest August on record still delivered 327 mm against 72 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 195 mm average is a reasonable planning figure, not a promise.

Wind is light at 6.6 km/h, so the temperature on the page is close to the temperature on your skin, and humidity at 86% is the real story though — it is the number that decides how the day feels, not the 30.7 °C.

How August sits in the year

Temperatures hold steady either side: 30.9 °C in July, 30.7 here, 30.4 in September. Nothing about the timing within the month matters much.

Daylight in August

Siem Reap sits close enough to the equator that daylight barely moves all year — 12.6 hours in August, against a range of just 1.6 hours across the whole calendar. Sunrise and sunset land at roughly the same time whenever you come.

An inland climate

Despite being inland, the year stays fairly even: 16.1 °C between the year's warmest afternoons and coldest nights.

How busy it gets

Shoulder. The value months — prices ease off and you get the place closer to itself.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

August in Siem Reap versus nearby

If Siem Reap is one option among several, the nearby comparison is worth making. Ubon Ratchathani is close enough to be a coin toss — within a degree on temperature, 2 days more rain. Nakhon Ratchasima is close enough to be a coin toss — within a degree on temperature, 1 day less rain.

So: August is a compromise. December is 29 points better and is what Siem Reap is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Siem Reap

See all twelve months in Siem Reap, or where else to go in August.