Mean annual rainfall in the country ranges from although most places in Vietnam receive between . The majority of rainfall occurs during the rainy season, which is responsible for 80%–90% of the annual precipitation. Generally, northern parts of the country receive more rainfall than southern parts of the country. Islands located in the north general receive less rainfall than the adjacent mainland while in the south, this is reversed where islands such as Phú Quốc receive more rainfall than the adjacent mainland. The annual average number of rainy days ranges from 60 to 200 in which most days have rainfall averaging less than . The amount of rainy days in a month usually corresponds with the mean monthly precipitation although in the north and north central coast, drizzle is common in winter (despite being the drier season), leading to higher amounts of rain days. For example, there are more rainy days in the drier season during winter in Yên Bái Province due to drizzle than there are rainy days in the main rainy season. Drizzle is a weather phenomenon that is characteristic of the weather in winter in the north and north central coast. Days with thunderstorms occur 20–80 days per year, which are more common in the south and north, and more common in mountainous areas than coastal delta. Thunderstorms can occur year-round although they are the most common during the rainy season. In the highest peaks in the north in Sa Pa, Tam Dao, and Hoang Lien Son, snowfall can occur.
