The climate of the country is subject to two monsoons per year, but the very different altitudes and latitudes cause extreme differences around the country. In the north, the mountains experience harsh winters; cold and snowy.
The south has an almost constant heat, accompanied by high humidity. To visit the north, the period between November and April is preferable for visits, when temperatures are cooler, especially at night, so avoiding the hot weather and typhoons from May to October and violent rainstorms in July and August. In the south, the dry and sunny season is from December to April.
The best times to visit North Vietnam are the months of milder temperatures, from late September to November and again in March and April. The winters in the North, especially in January and February, can get colder than you might expect, especially in the mountainous regions, with temperatures reaching 12-15ºC. The humidity is high all-year, making winters cold and wet and summers hot and humid. During the summer, the average temperature is around 30-35ºC. The rainy season lasts from May to September, and while rains can be quite heavy, the rain is not consistent and does not usually ruin a visit.
The temperatures in the Central region are milder than the North, with relatively warm weather year-round. The best time to visit is during the dry season from January to July, although these months can also be the hottest months. During the rainy season from August to December, rains can be quite heavy, particularly in the coastal areas. The weather in Central Vietnam varies more between destinations than other regions, with the weather becoming more tropical as you move south.
Southern Vietnam is in a tropical weather zone with year-round warm weather with an average annual temperature of 27ºC. Generally, the best time to visit is between October and February, when it is dryer and a bit cooler. The hottest months are March to May, followed by the rainy season from May to November. During the rainy season, rains can be long and heavy, but often are daily rains that clear quickly.