Vietnam covers a substantial latitudinal range, with temperatures varying depending on the elevation and geographical situation of each region. Distinct wet and dry periods occur across the year, though rain continues to fall year-round.
Southern Vietnam is the hottest region. When planning a visit to the south, it is best to arrive during the less humid winter months (December to March). There are two periods of heavy rainfall in the south: May to June and again from October to November. Between these monsoon seasons, temperatures crest well above 30°C.
The climate in northern Vietnam can be divided into four seasons. Humidity here is lower, making rainfall less of an issue. Trekking is better here, especially late in the year (September to November) when rain is scarce and temperatures range from 20 to 25°C. Temperatures rise significantly from April to June when average temperatures are higher than in southern regions.
In between these two regions, the monsoon season is consolidated to peak in the summer months (May to July) when the heat and humidity can put a dampener on outdoor activities. Across Vietnam, the wet, summer season is best avoided by anyone planning to spend time outside.