Last updated: July 2, 2025
Awareness of the UV Index is crucial for residents and visitors of São Mateus do Maranhão, Brazil, where the sun’s rays can be intense. Understanding the levels of UV radiation not only helps in preventing painful sunburns but is also vital for long-term skin health. With a tropical climate characterized by high UV exposure, especially during peak hours—where indices soar to 11 around noon—it's essential to stay informed. By knowing the UV Index, you can take proactive measures to safeguard your skin and enjoy the beautiful Brazilian sunshine safely.
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 in this region exhibits extreme levels throughout the year, with values consistently between 11 and 16. The high-risk months for sun exposure are from January to April, where the UV Index peaks at 16 in March, indicating a burn time of just 10 minutes under direct sunlight. Although the numbers decline slightly during June and July, they remain significant, hovering around 11 to 13. Visitors and residents are strongly advised to take precautions from January through November, particularly during the peak months, by seeking shade, wearing protective clothing, and applying a high-SPF sunscreen to mitigate the risks of sunburn and long-term skin damage.
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 Mateus do Maranhao | 15 | 14 | 16 | 15 | 13 | 11 | 11 | 13 | 13 | 13 | 14 | 13 |