When to Visit Phnompenh

Phnom Penh sits in the lowland plains of Cambodia, close enough to the Mekong and Tonle Sap rivers that the water cycle shapes almost everything about life here, including the weather. The city runs on a straightforward two-season calendar that most of Southeast Asia shares: a dry season roughly from November through April, and a wet season from May through October when the southwest monsoon sweeps in from the Gulf of Thailand. That said, "dry" is relative. Even in the coolest months, Phnom Penh tends to sit at around 70% humidity, which you feel more than any thermometer reading tells you. What makes Phnom Penh's climate somewhat distinctive among major Southeast Asian capitals is the timing of its peak heat. The hottest period falls in March and April, just before the rains arrive, when highs can push to 34°C (94°F) and 35°C (95°F) with very little cloud cover to break the intensity. By contrast, the wet season brings some relief. Afternoon downpours cool things down briefly and pull the highs back into the low 30s. September and October are the wettest months, with rainfall that can temporarily flood streets in the older neighborhoods near the riverfront. December and January are when Phnom Penh is closest to comfortable by any measure, with overnight temperatures dropping to around 21°C (71°F). Cool enough that locals sometimes pull out sweaters. It's still warm by most travelers' standards, but the drier air and marginally cooler days make the city considerably more pleasant for walking.