Last updated: July 2, 2025
Understanding the UV Index in São Luís, Brazil is essential for everyone looking to protect their skin from harmful ultraviolet radiation. With the coastal city experiencing a tropical climate, its residents and visitors face significant exposure to UV rays, especially during peak hours when the index can soar to an alarming 11 from 12 PM to 1 PM. By being aware of the UV levels, you can take proactive measures to prevent sunburn and promote long-term skin health, ensuring enjoyable time outdoors without the adverse effects of sun damage. Stay informed and safeguard your skin by checking the UV Index before stepping out into the sun!
The UV Index begins its ascent at 07:00 with a low reading of 1, gradually rising to 2 by 08:00. As the day progresses, the intensity of UV radiation peaks at 12:00, hitting a maximum of 11—a critical level where sun protection is essential. Following this zenith, the index starts to decline, measuring 10 at 13:00, then tapering off to 8 by 14:00. By mid-afternoon, the UV Index drops to 5 at 15:00 and continues its downward trajectory, reaching 2 at 16:00. As the sun sets, the UV index decreases to 1 by 17:00 and ultimately settles at 0 by 18:00, signifying the end of significant UV exposure for the day. It's a reminder that while the sun's rays can be intense at midday, the morning and late afternoon offer safer conditions for outdoor activities.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 2 | low | 45 min |
| 09:00 | 5 | moderate | 30 min |
| 10:00 | 8 | very high | 15 min |
| 11:00 | 10 | very high | 15 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 10 | very high | 15 min |
| 14:00 | 8 | very high | 15 min |
| 15:00 | 5 | moderate | 30 min |
| 16:00 | 2 | low | 45 min |
| 17:00 | 1 | low | 45 min |
| 18:00 | 0 | low | 45 min |
| 19:00 | 0 | low | 45 min |
The UV Index remains notably high throughout the year, with extreme exposure levels observed consistently from January to December. The months of February through March see the highest values, peaking at 16 in March, indicating a significant risk for sunburn with a burn time of just 10 minutes. While June and July slightly decrease to 12 and 11, respectively, they still maintain an extreme risk category. Visitors and residents should remain vigilant, especially during these months, and take precautionary measures such as wearing protective clothing, applying sunscreen, and seeking shade to mitigate potential sunburn and long-term skin damage. It is essential to prioritize sun safety year-round due to the persistent high UV Index in the region.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rio de Janeiro UVI | 15 | 14 | 13 | 10 | 7 | 6 | 7 | 9 | 11 | 12 | 13 | 15 |
| Sao Paulo UVI | 16 | 15 | 12 | 11 | 8 | 6 | 7 | 9 | 11 | 13 | 14 | 15 |
| Belo Horizonte UVI | 17 | 16 | 14 | 12 | 9 | 7 | 8 | 10 | 12 | 13 | 14 | 16 |
| Salvador UVI | 14 | 14 | 14 | 13 | 10 | 9 | 9 | 12 | 12 | 15 | 15 | 14 |
| Fortaleza UVI | 14 | 14 | 15 | 15 | 13 | 11 | 11 | 12 | 13 | 13 | 13 | 13 |
| Sao Luis | 14 | 14 | 16 | 15 | 13 | 12 | 11 | 13 | 13 | 13 | 13 | 13 |