Cambodia and Vietnam situated side by side, are often visited in conjunction with each other. Both countries are subject to two main seasons, wet and dry. High season for travel in Vietnam, Cambodia is from November through March but if you don't mind a few tropical showers here and there anytime is a good time to visit.
Northern Vietnam is generally warm from September to December, after which cold winter weather sets in, accompanied by fine persistent mists which can last for several days. Temperatures begin to rise again in March, building to summer maximums that occasionally reach 36°C between May and August.
In southern Vietnam the dry season lasts from December to late April or May, and the rains from May through to November. The best time to visit South Vietnam is May to November; expect tropical downpours in the afternoon. Travel is rarely affected by the rain and everything is lush and green at this time.
When is the best time to visit Vietnam?
There is no perfect time to visit Vietnam. Generally speaking, destinations in the north such as Hanoi and Sapa are great in October, November and December, as you'll see little rain and should have clear skies and temperate conditions.
The coastal stretch from Hue down to Nha Trang is great in the first half of the year, from January through to July, while Saigon and the Mekong Delta are best from November through to February or March.
The country is warm all year round, though there are several distinct seasons affecting the best time to visit Cambodia. 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 – mild enough to explore the temples in comfort but warm enough to sunbathe by the coast. Humidity and temperatures rise slightly during the hot season (March–May), with Phnom Penh and Battambang seeing peak daytime temperatures of 33–35°C.
This is an excellent time to visit the coast, although Angkor is usually bakingly hot. Visiting Cambodia during the rainy season (roughly June–Oct) can present certain practical challenges, but it is also a fascinating time to see the country as it transforms into a waterlogged expanse of tropical green under the daily monsoon deluges (fortunately, the rains falls mainly in the afternoon; mornings are generally dry). Getting around (particularly in September and October) isn’t always easy: dirt roads turn to mud and flooding is commonplace. Not surprisingly it’s also the quietest time for tourism (even Angkor is relatively quiet) and the countryside is at its lushest.