A tropical country, Cambodia is warm all year round, though there are several distinct seasons. There is little rain between November and May, the so-called dry season, which itself divides into two distinct phases. The cool season (Nov–Feb) is the peak time for tourism, as it’s cool enough to explore the temples in comfort and yet warm enough to sunbathe by the coast. The hot season (typically March–May) is when humidity and temperatures soar, with Phnom Penh and Battambang seeing peak daytime temperatures of 33–35°C. At this time, it’s best to rise early to get out and about, returning for a snooze at midday and emerging again late in the afternoon. This is also when the dust thrown up from the country’s dirt roads is at its worst, the billowing clouds ensuring that everything and everyone is coated in a fine film of grit. At Angkor, the unrelenting sun, allied to the lack of any breeze, makes for a baking visit, though this is an excellent time to hit the coast.
The rainy season lasts roughly from June to October. River levels rise dramatically, and in September and October the country’s infrastructure is at its most stretched, with dirt roads reduced to deep slurry and a risk of flooding in provincial areas. Thankfully, the rains aren’t unrelenting and fall mainly in the afternoon, so provided you don’t want to get off the beaten track and don’t mind doing most of your sightseeing in the mornings (which are normally dry), this isn’t a bad time to visit. It’s also the quietest time for tourism (at Angkor, you’ll have the temples pretty much to yourself) and the countryside is at its lushest.