Last updated: July 2, 2025
Understanding the UV Index is crucial for residents and visitors in Ha Long, Vietnam, where the sun’s rays can be intense, particularly during the midday hours. Recognizing UV levels helps prevent sunburn and protects long-term skin health, making it essential for planning outdoor activities. With a humid subtropical climate, Ha Long typically experiences elevated UV exposure, especially between 10 AM and 1 PM, when the index peaks at a striking 13. This makes awareness of UV levels not just a matter of comfort, but a vital step in safeguarding your health under the tropical sun.
The UV Index throughout the day showcases a striking pattern of intensity, peaking sharply around 11:00 AM and 12:00 PM with a robust 13, signaling a high risk for sun exposure during these hours. Early morning starts gently at 2 at 7:00 AM, then steadily climbs, passing through moderate levels at 8:00 AM and 9:00 AM, before reaching a critical point with a 10 at 10:00 AM. Post-noon, the index gradually declines, dropping to 6 by 3:00 PM and further to a much safer 1 by the evening at 5:00 PM and 6:00 PM, where it ultimately settles at 0 by nightfall. To enjoy the sun while protecting your skin, plan outdoor activities early or enjoy them after the peak hours!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 2 | low | 45 min |
| 08:00 | 4 | moderate | 30 min |
| 09:00 | 7 | high | 25 min |
| 10:00 | 10 | very high | 15 min |
| 11:00 | 13 | extreme | 10 min |
| 12:00 | 13 | extreme | 10 min |
| 13:00 | 12 | extreme | 10 min |
| 14:00 | 9 | very high | 15 min |
| 15:00 | 6 | high | 25 min |
| 16:00 | 3 | moderate | 30 min |
| 17:00 | 1 | low | 45 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 0 | low | 45 min |
The UV Index experiences significant seasonal fluctuations, peaking during the late summer months, particularly from April to October, where it remains consistently in the extreme category, with a maximum of 13. The highest risk months are March through October, when the burn time is reduced to just 10 minutes, making sun protection essential during these periods. Visitors and residents should take precautions, such as wearing broad-spectrum sunscreen, protective clothing, and sunglasses, especially during the hours of 10 a.m. to 4 p.m. When the UV Index is highest, consider seeking shade or limiting sun exposure to reduce the risk of skin damage. In contrast, the months of December and January present a lower risk with a burn time of 25 minutes and a high to very high exposure category, yet caution should still be exercised.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hanoi UVI | 8 | 10 | 12 | 12 | 13 | 12 | 12 | 13 | 13 | 11 | 9 | 7 |
| Haiphong UVI | 8 | 10 | 12 | 13 | 12 | 13 | 13 | 13 | 13 | 11 | 9 | 7 |
| Ha Long | 8 | 10 | 12 | 13 | 13 | 12 | 13 | 13 | 13 | 11 | 9 | 7 |
| Da Nang UVI | 10 | 12 | 14 | 15 | 14 | 13 | 14 | 14 | 13 | 12 | 10 | 9 |
| Ho Chi Minh City UVI | 10 | 13 | 15 | 14 | 14 | 12 | 13 | 14 | 13 | 13 | 11 | 10 |
| Bien Hoa UVI | 10 | 14 | 15 | 15 | 14 | 13 | 14 | 14 | 13 | 12 | 11 | 10 |