When should I visit Siem Reap, Cambodia, for the best experience?

Siem Reap's year is split by two monsoons rather than by temperature. The southwest monsoon brings the rains from roughly May to October; the northeast monsoon replaces them with dry, clearer air from about November to April. March and April are the hottest stretch of the Cambodian year, and that heat arrives before the rain does to break it.

The opening hours set by Angkor Enterprise, the government body that sells the temple passes, are what make the cool months worth targeting. The Angkor Temples Park admits visitors from 5:00 a.m. and closes at 6:30 p.m., a thirteen-and-a-half-hour window. Between December and February you can use the first two hours of that window without the fatigue that comes with an April morning.

Cambodia's travel advisory stands at Level 1, Exercise Normal Precautions, with the note that some areas carry increased risk. Health guidance matters more here than security: the US Centers for Disease Control and Prevention lists Cambodia among the destinations covered by its Global Measles travel health notice, Level 1, Practice Usual Precautions, dated May 28, 2025.

The temple roads run flat through dry forest, and in January the ground stays firm underfoot where in September it holds water. Dawn arrives fast this close to the tropics, so the 5:00 a.m. gate opening buys real darkness before the light comes up over the treeline.

Angkor was placed on the World Heritage List and on the List of World Heritage in Danger in the same decision, in 1992 — a simultaneous inscription and danger-listing that shaped decades of management of the site and the town beside it. Siem Reap grew into a base for that site, which is why its hotel capacity, airport and road network all point outward at the park rather than inward at the town.

• Pre-dawn — The park gate opens at 5:00 a.m.; being there at opening is the only way to be inside before the day warms.
• Late morning — Come back into town. Siem Reap's market quarter and riverfront are compact enough to cross on foot.
• Evening — The park closes at 6:30 p.m., which fixes dinner later than you might expect and makes the town's night economy the default.

Cambodia requires a visa of US citizens. Tourist and business visas are valid for one month from the date of entry, and you can apply online, at the Cambodian Embassy in Washington, DC, or on arrival at the Siem Reap airport — visa-on-arrival applicants need two passport-sized photographs measuring 4 cm by 6 cm. Your passport must be valid for at least six months beyond the date of entry and carry one blank page for the stamp. Immigration officials collect fingerprints on entry.

The things-to-do question in this group breaks down the separate ticketed parks around Siem Reap, which is where the multi-day pass arithmetic matters.