Hạ Long Bay, Vietnam: vitamin D, best months and travel guide
Thousands of limestone islands in green water. Best for: couples, photographers, cruise lovers.
The best months for vitamin D in Hạ Long Bay are March, April, October, November, when a full dose takes about 8 minutes at midday. Too cool from December to February and rainy or stormy from May to September.
Hạ Long Bay month by month
| Month | Rating | Sun window | Peak UV | Full dose, age 30 | Afternoon high | Rainy days |
|---|---|---|---|---|---|---|
| January | Too cold | 3.2 h | 3.8 | 14 min | 20°C | 15/30 |
| February | Too cold | 3.3 h | 3.8 | 14 min | 21°C | 11/30 |
| March | Good | 4.1 h | 4.7 | 11 min | 23°C | 11/30 |
| April | Excellent | 7.3 h | 7.1 | 8 min | 29°C | 15/30 |
| May | Bad weather | 8.1 h | 8.0 | 7 min | 29°C | 21/30 |
| June | Bad weather | 8.3 h | 7.5 | 7 min | 31°C | 27/30 |
| July | Bad weather | 7.4 h | 7.5 | 7 min | 30°C | 28/30 |
| August | Bad weather | 8.3 h | 8.1 | 7 min | 31°C | 26/30 |
| September | Bad weather | 6.1 h | 6.9 | 8 min | 30°C | 23/30 |
| October | Excellent | 7.1 h | 6.9 | 8 min | 29°C | 6/30 |
| November | Good | 6.0 h | 5.8 | 9 min | 27°C | 2/30 |
| December | Too cold | 4.3 h | 4.3 | 12 min | 21°C | 5/30 |
Sun window is the number of hours a day with UV Index 2.5 or higher. Full dose is the minutes at midday for about 1,000 IU of vitamin D with a quarter of the body bare, for skin type III. Rainy days are days with at least 1 mm out of 30.
What to expect in Hạ Long Bay
Thousands of limestone islands in green water. Different climates in the north, centre and south. The central coast (Da Nang, Hoi An) is best from February to May; the south is dry from December to April; typhoons can hit the centre from September to November.
In Hạ Long Bay afternoon highs average from 20°C in January to 31°C in August. The wettest month is July (about 28 rainy days out of 30) and the driest is November (2). Midday UV peaks at 8.1 in August, which is very strong, so protect your skin.
More about Vietnam · Vietnam in October · Best places in October
Questions about Hạ Long Bay
When is the best time to visit Hạ Long Bay for vitamin D?
The best months for vitamin D in Hạ Long Bay are March, April, October, November, when a full dose takes about 8 minutes at midday.
What is the weather like in Hạ Long Bay?
Afternoon highs average from 20°C in January to 31°C in August. The wettest month is July, with about 28 rainy days out of 30.
Which months should I avoid in Hạ Long Bay?
For a beach stay, avoid the months when it is too cool from December to February and rainy or stormy from May to September.