Vietnam is located in both a tropical and a temperate zone. It is characterized by strong monsoon influences, but has a considerable amount of sun, a high rate of rainfall, and high humidity.Temperatures are high all year round for southern and central Vietnam; but northern Vietnam has a definite cooler season as the north monsoon occasionally advects cold air in from China. Frost and some snow may occur on the highest mountains in the north for a few days a year. In the southern Vietnam, the lowlands are sheltered from outbreaks of colder northerly air and the dry season is warm to hot with much sunshine.