Vietnam has a tropical monsoon climate. Broadly speaking, the weather in Vietnam is dictated by two monsoon seasons -- the southwest monsoon from April to September and the northeast monsoon from October to late March or early April.

While people often equate monsoons with rain, that is only partly the case in Vietnam as there are a number of regional variations that affect the rain. What is worth remembering though is the southwest monsoon is hot and the northeast monsoon cool.

The southwest monsoon primarily effects Southern Vietnam -- warming up the Mekong Delta through Saigon and all along the coastal strip as far north as between Qui Nhon and Da Nang. It also influences the Central Highlands region.

The northeast monsoon effects the north bringing lower temperatures to Hanoi, Ha Long Bay, Sapa and the the coastal strip as far south as around Hue.

Temperatures only drop to what could only be considered cool in Hanoi, the mountainous north and the Central Highlands (in the evening). For the majority of the country, the temperature swings between the mid 20s to low 30s year-round.

Southern Vietnam, including the Mekong Delta, sees most of its rainfall between May and October, peaking in June.

The northern reaches of Central Vietnam see rain from August through to January, with the heaviest falls reserved for September and October which is also typhoon season. The southern coastal region, as far north as between Nha Trang and Qui Nhon, sees the rain start later, Novemberish, but still dropping off in January.

Northern Vietnam gets the wet from May to October, with August being the wettest month. The cooler months of December and January also see heavy mists that can run for days -- these can reduce visibility in places like Sapa and Ha Long Bay to frustratingly short distances.