Last updated: July 2, 2025
Understanding the UV Index is crucial for residents and visitors in Oeiras, Brazil, where the tropical climate brings significant sun exposure throughout the year. With UV levels peaking around noon, reaching a high of 11, awareness of these fluctuations is vital for preventing sunburn and protecting skin health. As you enjoy the beautiful outdoor activities this vibrant city has to offer, being informed about UV risks can help you take the necessary precautions to shield yourself from harmful rays. By keeping an eye on the UV Index, you can ensure a safer and more enjoyable experience under the Oeiras sun.
The UV Index throughout the day paints a vivid picture of solar intensity, peaking sharply in the late morning. At 07:00, the UV Index starts off modestly at 1, but by 08:00, it climbs to 3, indicating a gradual increase in sunlight. As the day progresses, it reaches 5 at 09:00 and then escalates dramatically to 8 by 10:00. The sun's strength hits its zenith at 11:00 with a striking 10, peaking even further at 12:00, where it soars to 11—an optimal time for sun protection. After this high, the UV Index begins to wane, falling back to 10 at 13:00, before declining steadily to 4 at 15:00, 2 at 16:00, and eventually drifting down to 1 by 17:00. As dusk approaches, the UV Index drops to 0 by 18:00, signaling a safe end to sun exposure for the day. Such daily fluctuations highlight the importance of being mindful of UV levels, especially during midday hours.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 3 | moderate | 30 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 | 7 | high | 25 min |
| 15:00 | 4 | 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 throughout the year displays extreme levels, particularly from January through November, with values consistently between 12 and 15, indicating a high risk of harm from unprotected sun exposure. Notably, the highest UV Index occurs in March at 15, closely followed by February and April at 14. Visitors and residents should take special care during these high-risk months and consistently throughout the year, ensuring they wear appropriate sun protection, including sunscreen, hats, and UV-protective clothing. With a burn time of only 10 minutes, it is crucial to limit sun exposure, especially during midday when UV radiation is at its peak.
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 |
| Oeiras | 14 | 14 | 15 | 14 | 12 | 11 | 11 | 12 | 13 | 13 | 14 | 14 |