The climate of Vietnam varies considerably from region to region. Although the entire country lies in the tropics and subtropics, local conditions vary from frosty winters in the far northern hills to year-round, subequatorial warmth in the Mekong Delta. All year round here, there is always a perfect place where it is pleasant to stay. Basically, the whole country falls into the tropic and subtropics but its stretching length and diverse topography allow it to span several different climate zones.
The North of Vietnam is generally cooler than other South East Asian regions in the same longitude. It experiences two main distinct seasons. In winter months, the weather gets colder and colder from November to March and considerably warmer in April (a leap into summer). This is also time to observe much cloud and frequent drizzle. In the summer (from May to October), the whole region is quite hot. Hanoi and coastal provinces around the Red River Delta generally enjoy equitable weather with high average humidity (80%) all year round though they may occasionally be subjected to typhoons and heavy rain in late summers.
The Central Vietnam with two sub-regions, coastal lowlands and central highlands, can be seen as an in-between climatic area of the North and the South. in particular enjoys nearly double the average rainfall of the country. Two biggest towns in this plateau, Dalat and Pleiku, are ideally cool throughout the year. Near-the-south coastal cities, Quy Nhon, Nha Trang and Phan Thiet, on the contrary, experiences steamy hot weather (21°C-32°C / 70°F-90°F) all year round.
The South of Vietnam, merely 8 degrees north of the Equator, is typical of humid tropical climate which is excellent for growing rice. The region’s temperatures experience little variations in a year (around 27-32°C/80-90°F). There are two main seasons: the rainy and the dry. During the rainy/monsoon season (from May to November), downpours are expected to happen nearly every afternoon, resulting in occasional street flooding in and around Saigon. In the dry season, it is hot from late February to April then slightly cooler when first downpours come. Ho Chi Minh City (Saigon) enjoys rather equitable tropical climate with high humidity all year round. December to March is said to be the most pleasant time to hit this region’s center.