Vietnam is affected by the monsoon, that's why the average temperature is lower than the other countries which are located in the same longitude in Asian. In comparing with these countries, the temperature in winter is colder and in summer is less hotter in Vietnam.
Under influence of monsoon, and further because of the complicated topography, the climate in Vietnam always changes in one year, between the years, or between the areas from North to South and from low to high). The climate in Vietnam is also under disadvantage of weather, such as typhoons (advantage there are 6-10 storms and tropical low atmosphere in year), floods and droughts are threaten the life and the agriculture of Vietnam.)
The temperature in Vietnam is high. The annual average temperatures range from 22 o C to 27 o C. However, the average temperature is different in every place. In Hanoi the average temperature is 23 o C, in Ho Chi Minh City 26 o C and 25 o C in Hue. Some places like Dalat and Sapa have a maximum temperature of 20 o C in the summer.
Every year there are 100 rainy days and the average rainfall is 1,500 to 2,000mm. The humidity ranges around 80%. The sunny hours is 1,500 to 2,000 and the average solar radiation of 100 kcal/cm 2 in a year.
The monsoon climate also influences to the changes of the tropical humidity. In general, in Vietnam there are two seasons, a hot and rainy season (from May to October), and a cold season (from November to April the next). However the four distinct seasons are most evident in the Northern provinces (from Hai Van Pass toward to the north): Spring, Summer, Autumn, and Winter.