Cambodia is a tropical country, meaning it is warm all year, but there are still 3 distinct seasons:
Dry season: November-February
The best time to visit, with temperatures in the mid to high 20's celsius (but be prepared for the occasional chillier night). It is also the most popular season, and the most expensive - Christmas and New Year, particularly.
Hot season: March-May
Humidity and temperatures rise steadily, peaking in the mid 30's in Phnom Penh, which makes the middle of the day an uncomfortable time for doing anything active. Be prepared for lots of dust, too, which all turns to mud in...
Rainy season: June-October
The southwest monsoon from the Gulf of Thailand drenches the whole of Cambodia. Dirt roads can become impassable and some areas flood, especially in September-October. But in Angkor the mornings are usually dry and you can have the temples to yourself, if you don't mind holing up in the afternoon, and being flexible on overland travel (or just using flights).
Note: flight, boat, train and bus timetables change constantly, and airlines come and go, so please do not rely solely on this information for your travel planning. Check with relevant companies, or a flight search engine like Skyscanner, first.
There are no direct flights from Europe, America or Australasia, so you'll have to fly into a regional hub (e.g. Bangkok or Kuala Lumpur) and take a connecting flight.
Flights in and out of Phnom Penh
Thai Airways and Bangkok Air fly from Bangkok.
Silk Air and Jetstar fly from Singapore.
Vietnam Airlines fly from Hanoi and Ho Chi Minh City.
Malaysia Airlines fly from Kuala Lumpur.
Lao Airlines fly from Vientiane.
Dragonair flies from Hong Kong.
Flights in and out of Siem Reap
Bangkok Air flies from Bangkok.
Vietnam Airlines flies from Ho Chi Minh City and Hanoi.
Malaysia Airlines and Air Asia from Kuala Lumpur.
Silk Air from Singapore.
Lao Airlines from Vientiane, Luang Prabang and Pakse.
Cambodia Angkor Air operate between Siem Reap and Phnom Penh. No other internal flights are currently available.
Arrange transfers with your hotel (they are sometimes included in the price) and they’ll pick you up at the airport. Buses do not operate at Cambodia’s airports. You might find a waiting taxi or tuk-tuk, but stories of overcharging from airports are common.
TUK-TUK AND MOTO
In the towns and cities tuk-tuks are the way to get about. They are not in short supply and hang out at all hotels and tourist spots, so you won’t have to wait. Be careful at night if you hail an unknown tuk-tuk in the city, as a tiny minority have been known to rob tourists. Motos (small motorbikes) will whisk you up the road, but won’t give you a helmet. Always agree the price before setting off.
Hire bikes - they’re everywhere and a great way to get about, especially in Siem Reap and Angkor, where you can follow your nose.
Buses run between the big cities; they are cheap, but not that comfortable and don’t get anywhere quickly, although they do show you the countryside and its towns.
The one bus route which is popular and reliable is from Phnom Penh to Siem Reap: National Route #6 is paved all the way, and the journey is faster than it used to be (5-6 hours). In Siem Reap the Chong Kov Sou bus station is located near Phsar Leu (the 'Upper Market') about 2km west of the centre; in Phnom Penh, buses from different companies depart from different stations.
This is a common way of getting around, especially in the wet season when some roads flood.
It's possible to take a speedboat from Phnom Penh to Siem Reap via Tonle Sap lake (typically 4-6 hours), but choose your vessel with care: the crossing can be rough, the boats overcrowded, and the lifebelts non-existent.
If you have time, consider one of the slower boat cruises (2-3 days) between Phnom Penh and Siem Reap. These are much more civilised. We recommend a cruise on Toum Tiou or Toum Tiou II, operated by Compagnie Fluviale du Mekong, which run from July to March (the river is too low from April to June). It takes 3 days, stopping overnight in the fishing towns of Kompong Chhnang and Kompong Luong, with accommodation in 10-14 air-conditioned ensuite double cabins, plus a restaurant and sundecks.
If you want to cruise in style along the Mekong and Tonle waterways in a replica of a colonial river steamer, offering luxurious cabins and smart-casual dining, try Pandaw, which owns a number of such vessels.