- Vietnam has tropical weather marked by a monsoon season. It is typically humid and warm, although the weather can vary significantly from one area to another due to the long length of the country which covers several weather zones and the variance in altitudes (in recently there has been aften snow in Sapa and Lang Son while it was quite hot in Saigon). The cold wind normally start from November to March next year in the North.

- Flooding is also common in the central coast region around Hue and Hoi An. Since flooding is common, most important for traveling in is avoiding the monsoon season which start from August to November. Flooding usuallu come with storms which are from China Sea. The flooding sometimes causes delay or cancellation for Reunification trains (from Saigon to Hanoi and return) or the domestic flights, especially the flight from Saigon to Phu Quoc or the flights to Danang, Nha Trang, Hue.

- Temperature remains almost constant in Saigon while in Hanoi there is a marked cooler, although pleasant season from November through March and warmer period during the summer ("cooler" is relative, you will not likely need a jacket). The lowest temperature in Winter (from November to February) in the North is about 12 Celcius Degree.

- During December, the weather north of Danang (and the Hai Van Pass) can be cool and rainy. January is an optimal month to travel the length of the country. However, Sapa does not thaw until around the first week of March.

- Specifically for Sapa, September through November and March through May are the best times for trekking and cycling in Sapa. Daytime temperatures range from 15-28 C, and night-time temperatures from 18 down to 10 Celsius. Trekking and cycling are possible at other times too, but the wintertime can be rather chilly, and the summer rather wet.

- There is one note that when you travel to Halong Bay from September to November, pay close attention to the weather forcast if there is any storm around the Tonkin Gulf to decide if you can take a night on boat in the Bay or not.