Last updated: June 2, 2025
Understanding the UV Index in Phu Thai, Vietnam is essential for protecting your skin and overall health against harmful UV radiation. The UV Index provides critical information about the sun's intensity at different times of the day—peculiarly high between 10 AM and 1 PM, when levels can reach a maximum of 12, indicating extreme risk of harm from unprotected sun exposure. With Phu Thai's Cwa climate, characterized by hot summers, residents and visitors must be vigilant and proactive in preventing sunburns and long-term skin damage. By keeping an eye on UV levels, you can enjoy the beautiful outdoors safely while safeguarding your skin’s health.
At sunrise, the UV Index begins at a gentle 2 by 07:00, but as the sun rises higher, the intensity quickly escalates. By 09:00, it reaches a moderate 7, signaling outdoor enthusiasts to apply sunscreen. The peak comes at 11:00 and 12:00, where the index peaks at a striking 12, indicating very high levels of UV radiation. As the afternoon progresses, the index gradually decreases, dipping to 8 by 14:00 and further dropping to 5 by 15:00. In the late afternoon and evening, the UV Index retreats to 3 by 16:00, finally settling at 1 by 17:00 and fading to 0 after 19:00. This daily cycle highlights the importance of sun safety during those 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 | 12 | extreme | 10 min |
| 12:00 | 12 | extreme | 10 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 8 | very high | 15 min |
| 15:00 | 5 | moderate | 30 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 |
| Phu Thai | 8 | 10 | 12 | 13 | 13 | 12 | 13 | 13 | 13 | 11 | 9 | 7 |
| Haiphong UVI | 8 | 10 | 12 | 13 | 12 | 13 | 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 |