Weather in Phnom Penh

On this site the months that score closest to a 22°C day, lighter rain, and moderate humidity are December, January, and February. Phnom Penh is in Cambodia at 11.6°N. The 2001–2020 NASA POWER daily record describes a monsoon climate with a sharp wet-dry split.

April is the warmest month (average 31.6°C, high 36.9°C) and November is the coolest (average 27.1°C, low 23.3°C). Rain is the monsoon runs from May to October, inside an annual total of 1242 mm. The wettest month is September at 190 mm; the driest is February at 11 mm.

When Phnom Penh gets wet

The monsoon in Phnom Penh starts in May and ends in October (May, June, July, August, September, and October). September is the core of it at 190 mm. February is the other extreme, with 11 mm.

A rainy day here is a day with at least 1 mm in the NASA POWER series. September averages 22 such days; February averages 3.

Hot and cool months in Phnom Penh

The heat peaks in April, when the typical afternoon is 36.9°C. The opposite pole is November, when mornings average 23.3°C.

Mean high across all twelve months is 33.1°C and mean low is 24.2°C. These are 20-year grid averages, so a city station can read a few degrees warmer or cooler.

The calendar in Phnom Penh

February is the driest month, averaging only 11 mm across 3 rainy days. Highs sit near 36.6°C. Peak heat arrives in April: 36.9°C by day, 26.4°C at night, and 60% humidity. May is when the monsoon typically starts in Phnom Penh: highs near 34.2°C, and rainfall jumps to 129 mm (19 rainy days). June brings 190 mm and 20 rainy days; temperatures run from 25.0°C to 32.0°C.

September is the wettest month — 190 mm and 22 rainy days, with 86% humidity. The year bottoms out in November. Plan for 23.3°C at night and 31.0°C in the afternoon. December stands apart from the months beside it: 32.3°C / 22.2°C and 28 mm.

Best months to visit Phnom Penh

The three months with the highest comfort score are December, January, and February: December (27.2°C average, 28 mm, 71% humidity); January (28.2°C average, 16 mm, 61% humidity); February (30.1°C average, 11 mm, 53% humidity). Those months sit across the year end, so they are listed in season order rather than January-to-December. The score rewards averages near 22°C, lower rainfall, and humidity near 60%. It is a climate score, not a festival or price calendar.

If you want the monsoon itself — fewer crowds, greener landscape, heavier rain — aim at May–October instead of the score.

How Phnom Penh compares inside Cambodia

Phnom Penh is the only Cambodia city in this dataset, so the figures on this page are the national sample we publish. They still come from the same NASA POWER daily series (2001–2020) used everywhere else on the site.