Ha Long features the coastal climate, so there are two distinct seasons in a year including winter from November to April next year and summer from May to October. Located in the tropical area, the annual average temperature is 23.2ºC; in the summer, the average temperature is 34.9oC and the hottest day is 38oC.
In the winter, the average temperature is 13.7oC and the coldest day is 5oC. The annual average air humidity reaches to 82.7%. The annual average rainfall is 1578mm, unevenly distributing according to two seasons. It rains more in the summer, accounting for 80-85% of the total annual rainfall. The highest rainfall is on July and August with about 350mm. Winter is the dry season with little rain reaching only about 15-20% of the total annual rainfall. The lowest rainfall is on December and January with only about 4-40 mm. Due to the characteristics of the terrain and geographical location, there are two types of monsoon in Ha Long including the northeast wind in the winter and southwest wind in the summer. Ha Long Bay is close sea are, so it's under less influence of the big storms. The average wind speed is 2.8m/s and the strongest wind direction is the southwest wind with the speed of 45m/s. Ha Long features not only the wonderful climate but also other advantageous socio-economic and natural conditions, that makes Ha Long increasingly becomes an ideal choice for tourists when coming to Vietnam.